Pros:

Awesome custom content
Great recreations of Disney Land
An amazing on rails sequence that was a blast
A unique finale
Great secrets and mission flow

Cons:

- Nav Mesh needs an overhaul
- Many open areas without zombie spawn points

Conclusion:

This map is great, and one of the best custom content maps I've played so far.  My only complaint comes in the form of the zombies having a hard time understanding the complicated nav mesh, and thus they don't tend to spawn in your way.  This problem is amplified by several wide open areas with no areas to block visibility and provide a zombie spawn.

A couple crashed parade floats and a reworking of the nav mesh (A map like this, in my experience, needs a primarily manually build nav mesh - the automated ones always act off like this) would bring this campaign to an easy 10/10 from me.  It's the only flaw to a great campaign, and it's one I think the developer can fix, too!

Pros:

- Objective based gameplay is always nice to see
- Neat missions, such as the escort the probe run
- An economy that requires you to proactively use the game world
- A ton of neat custom options to give the player control
- The riot shield makes it's return

Cons:

- An insanely simple map, but it's obvious the focus was scripting and is understandable.  It serves game play well enough.
- The medical vending machine is a bit exploitable if you hit up it's entire inventory every time you return to your base.  I ended up with piles and piles of meds this way.
- No counter or HUD element to indicate how many gnomes you currently have saved up, nor prices for specific items.  This can make buying things you want a bit of a guessing game.

Conclusion:

This is one of my new favorites from the contest.  Time and time again I'm seeing camping (which can be a lot of fun, if the map is designed for it) in a corner and abusing economy items in Let's Build maps, but this one totally avoids that by requiring you to go out and explore every inch of the map performing various missions.  That, right there, makes the difference.  The only shame is I don't think much time was put into the environment itself; this hurts a bit more here, as visual details can make the exploration aspect more fun.

I was unable to complete the map tonight, being a bit tired, but I'd definitely to give this one a shot.  It's a unique entry with some great ideas that I'd love to see in more maps of any genre.  This almost deserves it's own "Objective Survival" game mode.

I will be definitely trying to finish this one and return with updates if it impacts my review! 

PS: You can be hurt during the tutorial, and often hordes come, doing huge damage.  I realize this is a bug and I suspect it'll be fixed in short order.  

Pros:

- Cool setting idea, with some neat rooms and concepts
- Holographic escape vehicle is a creative idea
- Lots of buildables around the map
- Low gravity is a great touch.

Cons:

- Bile being so early on the tree renders all the defenses moot; it can be spammed indefinitely
- Bots can only arm themselves through the "Switch trick", which can be very tedious with weapons and supplies.
- Some defenses require an upgrade, but none could be found
- The map does not seem completable; after building roughly 5 minutes straight I added some to the ship, but an additional 10 minutes of adding happened and no visible progress was made, causing me to give up.
- Last but not least, the biggest problem:  There is literally no reason to visit the rest of the map.  Only one control terminal seems active, and everything you need is there.  The only defenses worth building are those immediately around the control panel as a result - maybe the halls - and then it's best to camp there, get an ammo pile, stack some medkits on the floor and just spam vomit jars indefinitely.  With the mob sizes, even tanks fall to this in seconds.

Conclusion:

A great starting idea.  When I was first looking around the map I found it quite entertaining, with some visual issues being made up for by a neat atmosphere.  However, once I found the control area, that was the last I ever had reason to explore the map.  I sincerely apologize if there is a reason later in the map, as I typically do not review DNF, but it seemed that I was either making no progress on the ship, or that it required so much time to advance each level it would have been another half hour of vomitjar spamming.

I think there's a lot of potential here.  I'd love to see this map repaired.  I'd recommend that you move the different tech trees to different parts of the station.  If you could only obtain Bile from one wing, and guns from another, and health from yet another?  You'd have a hell of a reason to move around your map and enjoy things like the low gravity.  Also a more detailed indicator of the progress on the ship would make building it infinitely more clear and satisfying.

Anyway, I'm hoping you decide to improve the map game play!  Seriously my biggest complaint is less with the overall map and more than that the way it's balanced, you have zero reason to ever explore or use any of it.  And that's a shame as I can tell a lot of work was put into the barricades and such.  Let me know if you patch, I'd be happy to increase my final score (which I'll admit gets a slight bonus modifier by my love for sci-fi maps.)

Pros:

- A hybrid building/scavenge system
- The map forces you to be proactive and not camp
- Difficulty seems in the sweet spot
- A smart move making bile and pipes rare, giving you only the molotov!  Bile is a life saver on this map.
- Forcing players between purchasing items and funding their escape route adds depth.

Cons:

- Some items seem priced too low; unlimited defibs for 3 makes things far easier than they would be otherwise
- The defensive structures only occasionally feel worth constructing
- Gas cans can be permenantly destroyed in accidents, but piles do not regenerate, which can render the map unwinnable in a disaster
- The bots like to jump off the really tall stuff to their doom frequently - some landings to break the fall could be helpful!
- Bots cannot use the gear acquiring buttons, forcing you to buy a second item to toggle and "drop."

Conclusion:

So far of all the other Let's Build maps I've gotten a chance to check out today, so far, my favorite bar none is this one.. there's a few quirks here and there (The SIG won't be active unless you have modded or used a change level, for example, making the most expensive item shoot blanks) but overall, I definitely had the most fun with this one.

Smart design decisions encouraging a proactive role in building your escape is a huge help.  I was able to play the map fine with bots by using the "Buy an AK47, then buy an Uzi so you can toggle and drop them" route, but it made things rough.  If you could make the items appear/drop instead of transfer directly to the character purchasing them, you would vastly improve the single player or low-player co-op experience!  It's rough having to manually buy medkits and pills for each bot.

None the less, these are mild things that can be repaired.  I wish you good luck!

Pros:

 - A good concept for a money system
 - Another good concept for the slot machines
 - A cool delivery method for your escape
- An overall fun concept

Cons:

- Slot machines can be triggered by hitting them with gun fire.  This results in bots wasting hundreds of dollars on items you don't want.
- While the upper tier fences state you "Get what you pay for" neither are better than the Chainlink Fence, which is the best deployable in the map bar none.
- Money comes way too quickly, so once you obtain T2 weapons including the Magnum, you can pretty much corner camp until you have money for the car.

Conclusion:

I've been looking forward to trying this one since I read about work being done on it over the Source mailing list.  It was a highly unique concept and I love the slot machine idea.  However, there's some gameplay balancing that I think would vastly improve the map's core systems.

Namely, the Chainlink Fence should be moved to the top tier of walls, and the others knocked down.  Second, gunfire should not trigger slot machines.  If you have even one maniac bot with a shotgun, you'll be buying dozens of items you don't want.  That hardly slows you down, however, as it seems corner camping as soon as the upstairs is walled off (a few walls can slow infected flow in the front yard, but are largely unneeded) is an extremely viable strategy.  You can hit the slot machine whenever you want to try for more gear and pretty safely dominate the map from this position.  It renders many of the coolest elements unnecessary.

Long story short, I think with some pricing changes and such this could be a great map!  I encountered a few bugs that I'll drop a PM to the author about, but definitely nothing crippling and I know first hand how hard it is to qaush them on a project like this.

I'm looking forward to the next patch!

Finally, putting a brief break in the early horde here and there would give the bots a chance to heal - as it stands, they will outright refuse to through the first 5-6 minutes resulting in a bit of an artificial challenge.

Pros:

- Isaac Clark finally gets a L4D model!
- First person arms add a lot
- Well animated without clipping issues many imports have

Cons:

- No helmeted version yet
- Metal needs an updated specular; looks like leather
- Medkits unfortunately blot out the health bar area

Conclusion:

I think if the metal parts of the suit can be given a more gruff, metal like reflective material (instead of the fully reflective/shared reflection with the non-metal parts of the suit), and the non-metal part gets less reflection, this will be a 100 for me; if I didn't know what they look like from Dead Space, I really would think he was wearing leather.  In fact I'm going to pre-rate it at 100 and cross my fingers for a fix on that because this is great in every other way.

I've wanted an Isaac model for personal testing of my campaign since I'm lacking character models, and finally I have one!

Pros:

 - Extremely long campaign
 - EXTREMELY tough campaign (this is a pro!)
 - Amazingly well polished

Cons:

 - A small handful of very minor glitches
 - As mentioned, the horde doesn't shut off during the finale tank.  This is only really a problem if you're trying the campaign out solo, and can only carry one grenade at a time; I was able to escape by ditching the bots as decoys.  I appreciate what you're going for here - I think it could be fixed simply by adding a few more bile / pipes in the area where the tank spawns, so you have a reasonable chance of getting one.  This would also fix Versus, which would be outright impossible this way; another idea is to add two tanks (instead of one) and provide more physics cars.  As it is, it's only really possible with a full grenade wielding team.
 - The Church is a bit confusing, with no indicator how to open the door; the bots don't follow you to the exit until you go there yourself.  It took me several minutes to figure out how to get out of it.  Only part I got lost in, though!  Great atmosphere - adding a Hint would fix this.
 - As a minor bug, the ending was broken for me; it "killed" me while in the credits, and I saw 0 for most stats (such as kills)

Conclusion:

I'm disappointed this isn't even higher rated.  Frankly I think that some people do not like very rough campaigns, where ammo is very scarce and Tier 2s are extremely rare - something you need to go out of your way to find.  They also might not like maps with lots of exploring.  I'm the reverse on every count - I loved this map all the way through and the difficulty is what put it over I Hate Mountains for me; it's a rough map that punishes you (The message on the map 2 saferoom is hilarious) and makes victory rewarding.  Hell, I had a rough time on Advanced with bots, though managed to not die until the last map from the tank / not realizing that the gauntlet path was random on my first go.

Also I really like how it makes heavy use of the Defibs, and has little to no closets - I never had an ally come back at a closet, but there were enough defibs that I was able to revive them all, with the exception of Coach falling off a cliff.

Highly recommended.

Pros:

+ A good entry into a new genre
+ Fairly difficult and well balanced
+ Well polished
+ Nice atmosphere and premise

Cons:

+ Bots refuse to enter the rocket, require kicking
+ Tricks needed to supply the bots with weapons
+ Minor changes in the tech tree needed

Conclusion:

I really dig the game type.  I've been working on build & construction maps for a campaign myself, and think it's definitely a new emerging genre for Left4Dead.  It's a really fun map in general!  

A couple issues I noticed I hope you'll get a chance to patch up:

One issue that greatly brings down the difficulty is the Gas Can being so low on the tech tree.  If you purchase this early and steadily burn it, things become almost too easy very quickly.  I was getting items/teching up twice or building a rocket part for every single gas can used, which due to their AOE made the increasingly hard waves of zombies a non-issue.  Likewise, more points of entry to attack you from might render this issue obsolete.  The end game for me was equipping everyone with an M16 and just making sure to have 3 gas cans in reserve, replacing them near the chainlink fences in front and simply building a rocket for each gas can burned.  However, this trick does make the map completable in single player, where otherwise it might not be.

Second, equipping bots.  It'd be much nicer if instead of using the Giver, you used an entitymaker that would spawn the items somewhere near the control panel, rather than directly to the player.  That way the bots could more easily be armed.  Right now the only way to accomplish this (and is pretty vital to winning the map alone) is you need to purchase two primary guns (Uzi, Silenced Uzi for example) and give yourself one, then the other and repeat.  The old weapon will fall to the ground, at which points the bots will pick it up.

As mentioned in the cons, the bots refuse to board the shuttle.  The closest they'll get is the stairs - I would be entirely accepting of a Survivor Pusher to move them up.  Right now the only way I could win the map was to go to the console and outright kick all the bots - and I tried for quite a while.  A minor issue as this map is way more fun, no doubt, to be played with humans.

Finally.. I'd love to see a Survival version (given the kind of map it is), perhaps with a score awarded on how many rockets you send up or something to that effect.  Or, even cooler would be to have multiple arenas and teleport the survivors to the next one after a "victory."  The main reason being that the increased Special Infected and tank waves would be a huge help to the game.

Anyway, I'll be watching this one for updates!

Anyway, I'm still voting 100 because it's an entertaining entry into what I hope can become a popular genre and I think you can easily sort out the problems in a patch.