Pros:

Excellent design.
Excellent new props, music and voices.
Good ammo balance.
Scavenge part, very well implemented in the continuity of the campaign.
Tons of fun.
After all, it's our favorite archaeologist.

Cons:

Short.
I was expecting more deadly, Indy-style traps.
Bots will inevitably trigger all the touchplates.
I know it's a rendition of a ride, so the "hallway effect" is normal, but still the maps feel a little bit too much linear.

Conclusion:

Short and sweet. Recommended. Even if it's for L4D2.

Pros:

Challenging
Very long
A lot of new props and tricks (loved the radio!)
Excellent finale concept

Cons:

Way too much ammo, not enough throwables
Littered with graphical glitches caused by incorrectly placed standard props
Boring interior places, everything is square
The ending wasn't really on par with the finale
The English is pretty bad

Conclusion:

This campaign has maps that develop a lot vertically, upping the challenge since survivors have to constantly watch their step. Despite way too many things looked wrong, it was all extremely fun.
Oh, at a certain point, map 2 or 3, I don't remember there's a sofa, an extremely inviting sofa, but jumping on it will cause the stuck-while-in-falling-animatiion glitch. Annoying.

Pros:

All original and new panic events.
Gauntlets? In my L4D?
Huge maps leading to two tanks per level.
Great ammo balancing.
One of the most entertaining finales ever.
The logs and medical clipboards, although nothing really original or never seen before, add some depth to the campaign.

Cons:

All exterior zones are poorly detailed. Some buildings suffer from the same problem.
The finale's workshed is way too secure. Breakable walls should be added.
Missing textures for the explosions on the bridge.
Sometimes supplies are so scarce you will be begging for a pipe just because you're tired of entering rooms with nothing of interest.
A few graphical glitches here and there.

Conclusion:

The first time I played this campaign I totally fell in love with it. It makes me sad to see that a lot of people rated this low because they got lost. At this rate L4D3 will have a GPS system included so people can understand that if there's a road that's where they want to go.

Anyway, while i love it, it's far from perfect. Unless you have absolutely no sense of direction you should give it a try - keeping in mind it's an ''open world'', not a hallway.

Pros:

Challenging
A lot of items hidden around the maps
Some nice props
Most maps get two tanks
Interesting finale activator and vehicle
Overall well balanced for advanced
Very long

Cons:

Design is nothing exceptional, most locations are rather empty
Extremely redundant, all the places look like the ones before
Every panic event is either a switch that opens a gate or an elevator
The gates open way too slowly. For most of them we just had to wait, 'cause no zombies were coming either way
Bots fry themselves on the metro tracks
The final map is a bit too long
Very long

Conclusion:

When my friend and I finally hit the rescue vehicle after 2 hours on Advanced, my feelings toward this map were a mixed bag. I loved the relentlessness of the constant hordes coming (5083 total zombies killed) and I had a lot of fun, but when I wasn't fighting zombies it was rather boring.
I'm not saying you shouldn't try it, just keep in mind it might leave you a bitter taste that you can't describe. I know it did it to me.

Pros:

Very fun to play and nice to look at.
Good ammo balancing.
Extremely unpredictable finale twist.

Cons:

Short.
Not very challenging, with the exception of the last panic event in map 2 and the twist in the finale.

Conclusion:

Strongly recommended for a quick game (less than 1 hour on a first try).

Pros:

Interesting maps.
Nice ammo and weapon shortage in the first map.
The relentless waves in maps 3 and 4 make it very challenging.
Twin tanks!

Cons:

Nothing new concerning the design of the areas.
Too many locked doors that look like real doors.
The ammo shortage at the start quickly turns into an excessive amount of ammo piles, with a couple of exceptions in map 3.

Conclusion:

Fun was had with this campaign, but it is far from perfect. Overall, it's still a thumbs up!

Pros:

Excellent rendition of Doom's level.
Exploding barrels.
Use of keycards (although, some audio or visual reminder that a player has collected them would be neat).
All the graphics and props look the way they should.

Cons:

Way too easy and short.
Bot unfriendly: they can't open doors and pick up most items.
No finale.

Conclusion:

The amount of common infected should be *at least* doubled, same goes for the SI.
A finale should be added.
It was fun, but the kind of fun that lasts for only 12 minutes. Unfortunately I can't give it more than 65.
It's worth a go, but you won't be replaying this map anytime soon.

Pros:

Excellent design
Huge, well detailed areas
Excellent gameplay, well planned hordes and events
Overall high replayability

Cons:

Missing supplies in some of the saferooms can up the challenge a bit too much, especially if the players don't know it in advance and plan according to the "usual" rules
The lower part of the skybox in the finale doesn't look right
Bots have the usual problems with navigation

Conclusion:

This is one of my favorite campaigns. Very recommended.
Please note: there have been *great* improvements on the gameplay since the version reviewed by Kilplix N Friends.

Pros:

Very challenging

Cons:

Messy design
Poorly cluttered: the same few objects over and over
Extremely linear
Events started by walking in specific spots rather than by activating an object
Special infected can somehow activate the spots above
All in all, not much fun to play

Conclusion:

I never like to pan a map like this, but it really shows that the author didn't put a lot of effort and creativity in making this one.

Pros:

Great design and detail
Challenging
Exploding barrels

Cons:

Quite short
Many problems with zombie and bots navigation: hordes occasionally couldn't get to us and the bots often stayed in place until the game decided to teleport them. Also, stupid bots don't know how to stay away from the electrified fence.

Conclusion:

If you like your daily close quarter claustrophobic zombie slayage you'll definitely love this map. I couldn't find any ammo on the finale area, which can be quite a problem, but I didn't put it as a con since it might just have been me being blind.

Pros:

Solid looks
Solid gameplay

Cons:

Not extremely exciting so far, maybe I just got unlucky with spawms
Incomplete (this is not affecting my rating)
On the first map the oxygen tanks used to blow up the wall can incap the whole team. I don't know if this is intentional, but it was a very cheap trick. Incap one player - good fun; force a restart - very wrong.

Conclusion:

I'll definitely check this campaign out on the next updates. You should too.

Pros:

Replay part of HL2:E1 on L4D.
No HL2-related architecture, everything has been reworked to fit L4D's "lore".
Length and difficulty on par with official maps.

Cons:

Some lighting issues where textures are over-reflecting light sources.
Some infected appear to be stuck on the ceiling (seen mostly in the underground zones).
Occasionally too many specials in a row.

Conclusion:

Whether you've played the game or not, this is a fun map that deserves to be played.
Bots manage to find their path most of the time.