Pros:

Imaginative environments, rich in details

Many alternate routes, alternate events

Custom voice acting

Custom melee, whack the crap out of the undead with their own body parts!

Cons:

Low fps in certain parts. For myself, the worst part in the whole game in on map 3 (I think), when you drop from a hole in the floor to a smallish flooded lab. 

Strange bug at the onset of map 3 where I see blue artifacts flickering around me.

Conclusion:

Superlative campaign, way up there with Suicide Blitz 2 and Back to School.

Pros:

Amazing locations.
Maps are very long, which I like
Great ending with opening jail cells

Cons:

Too many throwables and health items,
Too many lv 2 weapons and katanas early while safehouse continues to give you lv 1 weapons for a while.
Certain areas had too many specials, like 6 within 10 seconds.

Conclusion:

Great maps layout and very cool ideas like the collapsed bridge and jail cells. The streets are too empty and bland though. 13 gas tanks was perfect, the rest is too easy for me. 

Pros:

- Amazing recreation
- The custom soundfile makes the journey much more vivid
- Long with lots of explorable area
- The refillable gas container finale was new and interesting.

Cons:

- Rather bland action. You get all the L4D2 cliches one after the other, the bathroom with a zombie in one stall, the kitchen area, the storage area... Map 1 & 2 were rather boring and lackluster.
- The haunted house event is very long to start. Actually, the whole thing is very much like Night Terror, but less fun.
- Too many single gun pick up that means if you're not fast enough, you always end up with a gun you don't like.
- Much too easy. Almost no hordes, 1 tank before the finale and long stretches without specials. Even with 3 bots on advanced, I never had to heal once on my first play and neither did any of the bots.

Conclusion:

Must have taken you a freaking long time to create! Nice layout and fun to explore once, but not fun enough to play again a second time.

Pros:

- Amazingly fun and varied
- Interesting ideas such as hiding the gas cans in bearable crates, the cluttered sewer level, the music club, etc.

Cons:

- The load times are particularly long compared to other campaigns.

Conclusion:

Excellent campaign, one that I would play frequently.

Pros:

- MUCH more fun than I expected
- Research, defence building, all requires teamwork

Cons:

- Most important one: Bile. Its very easily accessible and as soon as you get it, it's game over. You can just spam biles and never be in any trouble.
I think the tree should be: 

air tank > propane tank > gas tank > Pipe Bomb > Molly or Bile. 

- Bots do not enter the rocket. They also cannot grab any weapons or health items, but that's not something you can do anything about. 

Conclusion:

Really fun, I can't believe I held off for so long on this one!

Pros:

Very good looking maps, professional layouts with some side paths.

Good amount of supplies

No major bugs

Cons:

Ridiculously short. Three maps that aren't very long to begin with means less than 20 min gameplay for a veteran player.

Map two and three feel a little bit repetitive. You could break them in the middle with a different-looking section to give a little more variety.

Conclusion:

Seriously, add 2 more maps of the same caliber to this baby and you'll have a real winner! 

Pros:

-You did a good job on the maps port, everything is smooth and generally bug free.

-HL2 map selection fits well with the zombie apocalypse theme.

-Useful .50 cal. at the end, one of the few times in L4D the turret is actually well placed.

Cons:

-Maps are ridiculously short. Without the tanks, 1 & 2 could be aced in under a minute.

-Each map has a tank, a witch and large number of special infected almost straight out of the safe room.

-Not a single gun other than the one you start with for the first 2 maps (unless I missed something hidden somewhere).

-Bots don't teleport with you on map 4. And as a tank waits on the other side, I was screwed.

-I don't remember having this issue with HL2, but certain sections have a contrast that is way to high. For example at the beginning coming out of the train, half the station, trains, characters etc are just matte black except when you flash your light on it. Looks very weird.

-No voice for the radio at the end.

-After defeating the last tank at the finale, I got the message "Rescue has arrived" but nothing materialized. Then we were teleported to a safe room with the credit music rolling it. It's missing an escape vehicle.

Conclusion:

Interesting to play these maps in L4D 2 but it doesn't really translate well as a full fledge campaign. The whole thing could be 1 or two maps, not five.
It also lacks weapons and items. 

Pros:

Visibly, the work of a mad scientist mapper
Unlike anything you have played for L4D!
Hard, fun and challenging.
Random traps on floor, random doors to open keep you guessing every time you play.

Cons:

An exploit allows you to skip the alarm on the second map where floor is flooded. Now since everyone knows it, it became a bit too easy.

Conclusion:

It's a love it or hate it kinda campaign, it seems, but I think everyone should at least try it once!

Pros:

The most original and crazy campaign is back with a vengeance! 

Challenging puzzles for the limited l4d tools you have, congrats galore, you insane map maker!

Graphically appealing, a technological psycho-circus on acid.

Extremely varied and unpredictable.

Cons:

Over reliance on the grenade launcher. It could be really interesting if some puzzles had to be done by snipping. 
 

Conclusion:

It's in the same vein as the original QE yet very different, which is a good thing. However the over use of the grenade launcher got repetitive faster than the gas tanks collecting could get in part 1. I'm not sure if you would modify the first few levels at this point anyway, it's a great campaign none the less. Cannot wait to see what's in store for the finale. 

Pros:

Harder than most custom campaign.

I like the acid fountains on the first map, everyone gets a bad surprise the first time around!

Original map layout. never confusing yet surprising most of the time.

Cons:

It is possible to start the crane event even if some players are not on it, thus stranding them there.

That crane section has some navigation issues. first, if you jump down on the wood scaffoldings from the second building, you can cut through almost half the level by going around the building and jumping down on the pierced roof under the level's 2nd crane.
Second, it is also possible to jump/fall from that second building to protruding parts of the 1st and so make you way down to the streets from which you can't go back anywhere.

Conclusion:

This review is for version 1.1 (beta).

I like it so far enough to keep playing it. I would say fix the crane so that it cannot be activated until everyone is on it. Also, barricade the streets below so that you cannot walk off the map (which you now can) and had a few crates next to the truck that blocks an alley so that if you do fall down for whatever reason you can at least go back to where you're supposed to be.

Alternatively, make the streets navigable as a second route you can take if you miss the crane! There are a lot of good snipping positions on the roof from which you could get covered. You could maybe climb back up the second crane that already has an infected ladder on it or through another building door. 

Pros:

The absolute pinnacle of custom campaign design for L4D2

The environments are properly detailed and varied. 

Exciting, exciting, exciting. The stadium finale is NOT recommended to anyone with high blood pressure!

The amount of work you put into the eater egg is staggering and definitely adds replay value.

Cons:

Only 1 minor. In the finale, the radio message you have to listen to before the gate opens is rather long. The fact that you have to wait for everyone to get ready before you can even activate it makes the way even longer. If you could find a way to shorten the dialogue or at least put the radio down so that we can activate the dialogue early. The gate could still not be opened until all 4 players are in the short corridor stretch next to it. 

Conclusion:

Probably the best custom campaign there is, one that rivals the professional ones built into the game. VERY HIGHLY recommended!

Pros:

Action-packed and different

Rail shooting through an infested world is fun as heck!

Interesting map layout.

Cons:

Virtually unplayable in single player because the bots do not jump on the truck. I ended up having to kill them all and hoped not to get jumped on while i reached my destination. 

As someone mention, front mini gun is impossible to reach when the truck is moving. 

Conclusion:

If you can fix the bot issue, this map would be killer jump up in rating. I would love to see an official L4D2 port too so that lots more players could jump in the action. 

Pros:

You want originality? Here it comes!

Challenging and fun!

Brings a brand new gameplay style to my good old L4D2

Fire breathing alien dragon, oh my!

Cons:

I wish there was a fourth map somewhere in between. It's so much fun and fast-paced that it feels a bit too too short.

Bots do not understand they have to shoot the circles on flying enemies. At least they gave me good cover!

Conclusion:

I love it. I did not experience ANY lag whatsoever personally on my Macbook pro 2.66GHz core i7 with nvidia GT 330m.

I did find the final level of the campaign very hard at first, but once you understand what you have to do, I can beat it without using a single health pack at normal, and with 2 at advanced. To me its just perfect.

Pros:

The sewer level is probably the most impressive custom level I have played, very well done!

The helicopter with the mini guns at the beginning is a very nice touch.

The windows that can be boarded up in the finally is a pretty cool idea too, I'm surprised it isn't used in campaigns more often.

Cons:

The hotel level is very bland and repetitive.

I didn't find the overall campaign or finally to be that exciting. 

Conclusion:

You added many little touches here and there that sets this campaign apart from most L4D 1 user campaigns. I still felt it was lacking a little something to really bring it up to the top tier but it's definitely worth a download!