Pros:

- Looks absolutely beautiful; dilapidated environments are quite appropriate and suitable for the zombie apocalypse.
-  Unique levels and intense crescendo events.
- Bots navigate fairly well.
- Weapons and health items are quite fairly distributed. 
- Atmospheric music.

Cons:

- Corpses immediately disappear on the beached barge level after killed... I'm not certain if this can be adhered to though...
- The escape felt pretty lacking... the environment was great, but I meant the vehicle itself. The balloon could be manned, or the waiting period could be the inflation of the balloon. 
- Tanks and witches spawned in very inconvenient  places; such as a tight corridor when we all had Tier 1 weapons. 
- The sea reflected the purple checker texture...

Conclusion:

Looks and plays fantastic and was a joy to navigate and explore. This is definitely worth a download. However, the finale was confined to a small area with a lack-luster escape and there's a couple technical problems...

Pros:

-Original
-Building barriers is effective, intense, and rewarding.
-Difficulty ramps up as the game progresses, more common and special infected pour in.
-Fair amount of special infected and tanks.
-Well thought out and balanced item acquiring and progression.  
-So many things to build that distract you from the rocket.

Cons:

-Special infected spawning is predictable.
-Map is small.
-Environment is bland.
-Bots are utterly useless, they can't acquire any weapons or health items you unlock, they're stuck to using only a pistol and using what health items you give them the whole time.
-Techno music playing in the background is nice at first, but it eventually gets annoying and distracting.

Conclusion:

Original, fun, rewarding, great with friends. However, it's not much to look at cosmetically and bots are absolutely useless. So when you're like me, a guy who has no friends who own L4D2, and considering no one ever hosts custom maps other than Suicide Blitz, No More Mountains, or Blood Tracks, it's impossible to play in single player, although it's usually your only option.

Pros:

-Beautiful! Looks EXACTLY life Team Fortress 2!
-Cart works perfectly, as it does in TF2
-Plays well with AI for the most part.

Cons:

-Items are too far and too few in between, and medkits are only in the three BLU spawns.
-Not much reward for straying off the obvious path.
-Too many common infected.

Conclusion:

Great idea, and it's executed well for the most part. However, your weapon will run dry quickly, and you'll die around the second stage in all probability.