Amazing.
The only issue I had was the (I assuming) randomization involved with finding survivors. Some games I'll have 4 to 5 survivors most of the time, some games I'll never have more than one (and even that one, I'll only keep for one night)
That aside, this game has very high replay value, great graphics, and is just overall very, very good for a flash game. I've seen console zombie games that were nowhere near this good (IE "Land of the Dead: Road to Fiddler's Green")