Yahtzee has hit the nail on the head as far as I'm concerned. This is more or less what I thought of the game. Unfortunately I usually have to play with only 1 other human player (due to the lack of internet/alternate 360), and at times in Expert, the human AI seems hellbent on getting the rest of the party killed. They wander off at odd times, decide not to shoot at others, and generally make terrible decisions on how to stay alive (IE: Not run away from the Tank. Just stand there shooting at it... Or deciding to startle the witch)
But if you are able to play with a full team of actual people, the game is quite hilarious. The general complaint from many people I play with is the lack of a melee weapon (machete, ax, crowbar, hammer, other things mentioned in the official zombie survival guide), however, you don't really need one, especially when playing on the harder difficulties, normal zombies die in about 4 hits, and the bigger ones you don't want to get near anyways.
I do wonder how long Yahtzee played the game, as there were very little references to many things in the game I would've considered irresistible, like any mention of the witch, burning tanks, shooting the cars with alarms in them.. Or having bitter teammates you accidentally shot.. many times.. til they died.