FUCKING AMAZING!
far better than the first one. more levels and more upgrades.
one tip for users. if you are pretty good then choose nightmare, and stick to the shot gun, granades, claymores and railguns... when you beat a level, find the main spot, or only spot, where the zombies come out of, then place as many claymores as you can in front of it and just get the fuck out of there.. then whip out your shot gun or railgun and shoot while the claymores go off... you'll rack up a lot of points this way!! [shot guns are your friends!!!]