Pros:

long campaign, but in a good way
original maps, really enjoyed the ballad
good balance for the difficulty/number of zombies

Cons:

invisible walls (i saw only a couple)
skybox goes crazy when lights are off, so you have to keep it on, i don't like it :D
FPS where going down when under the rain, didn't experienced it in "hard rain" for exemple
i confirm that server crash when outro begins

Conclusion:

Just played it with my friends. We loved this campaign ! As said before, few bugs to solve, but nothing really anooying. Really liked it, think we gonna play it again.