There's no game as fun when all you want to do is kill some zombie's with a crowbar or chainsaw.
I like the maps however i think there should have more, after playing the game a few times over the maps become boring and you find yourself loosing the fun factor and becoming a little bored yourself.
I think there should have been a story-line to the game to motivate the brains of people playing, and the campaign that it currently has should be part of the online process. but all in all i think its a game and a classic at that, and certainly original.