Straight up shoot'em up with fun local multiplayer...
If you are looking for a game with more intelligence quite frankly this isn't it, it's just a point and shoot game, which again in my opinion is enjoyed with a couple of friends. The ability to wreak havoc on the zombies simultanously with upto four players is quite fun.
The graphics and sound effects aren't the best but they are not the worst either. All in all this is an OK game where your only aim is get through each day (wave) staying alive.
It isn't a game you'll miss on but if you have a couple of extra bucks and a lot of friends visiting you, you'll definitely enjoy this game.