Pros:

Great music
perfect textures
good paths ( ladders, tunnels, stairs and ramps )

Cons:

the intro music is very stupid but when you blow horn the good music start 
miniguns are boring you can survive infinitive
map is to big
gameplay is wierd, common infected doesnt come to king throne room

Conclusion:

I like the l4d2 version more, this is just laggy and doesnt have defibs although it was fun to explore but gameplay is horrible.

Very fun and easy to defend