Pros:

-For the most part, the level design is quite good.
-Hordes are challenging but not too common.
-Special infected are a real pain in the dark.

Yeah, about that darkness.......

Cons:

-Too dark.
-Too dark.
-Too dark.
-Too dark.
-Too dark.
-Too dark.
-Too dark.
-Some questionable design choices on events.
-Level design can be awkward in some areas, though this is fairly uncommon.
-Tanks?

Conclusion:

A potentially great campaign marred by the absolute worst lightning you will ever encounter. 80-85% of the map area is pitch black, and the rest is not much lighter. This leaves you relying on your little flashlight to see *anything*, which lasts pretty much the whole campaign. The fundamental premise of the campaign is its most grave flaw; I understand the author was trying to go for a more survival horror sort of approach, but this approach fails for a few reasons:
1. Left4Dead is not a survival horror game; it is an action game. Resident Evil 2 is a survival horror game. Go play it, and see how the two games differ greatly.
2.The campaign seems to want you to move more slowly and carefully amidst the darkness. But, moving slowly through the darkness is going to cause hordes to spawn on you. In the darkness, hordes are a true pain to fight..especially on expert.
3. Basically, refer back to 1. All of Left4Dead's game mechanics rise from it being an action game. This campaign begs you to take a slower approach, which is frustrated by the dark, dark, *dark* lightning. It's hard to be careful when being careful spawns hordes that you can barely see.

I never saw tanks in the maps, aside from a scripted one as part of an event on map 3. This event was a *highly* questionable design choice because you have to push a button and open a door to activate the event, and the tank bursts through the door immediately, right on top of you - and did I mention you're stuck in a narrow corridor, and the way you came from is sealed so you can't go back? Good luck managing it on expert. This is what made me throw down on my first try.

Also - the speeding car part was neat, but that should have been an event. It made a roaring noise when it crashed, but the commons just stood around. Missed opportunity for a neat, unique event there.

The map design itself, however, is really very good. It's just too bad you don't really get to appreciate any of the details because you can't *see* any of them due to the darkness. The darkness just kills this campaign, and it's nonsensical too - especially outside. The moon gives off moonlight too, you know. This campaign would be a 90 if it were a bit brighter.