Pros:

-very clever
-Feels like a maze or puzzle
-I particularly enjoyed the rooftops, Very large
-Dark skybox gives a really urgent feel to the level

Cons:

-could use some work on ammo pile locations (Too far apart)
-The actual roof part of the rooftops felt empty, could use some items on top
-At the very beginning, i Have restarted over and over, but it always kills ellis for me before you can do anything, so you play the first chapter with three players.

Conclusion:

I think it's got some way to go, but all campaigns start from somewhere. this one is definitely going places, I can't wait to see where this map goes, it could be really great, possibly as good as an official campaign! Cold Stream was pretty bad, and now it's finished and looks good. This map, i can see, is already ahead of where that map came from. I know that this map -with required revisions- is going to be fairly popular community-wise :D