Summary: Got it for the steam Halloween sale for 2.50, and deleted it after 8 hours. As stated in the other reviews its not bad, but its not good either. I just got bored with it, and realistically I have so many other games Id rather play I'm never going to touch this one again.
Summary: As (at the time of writing) the only other user reviewer has said - save your money. Shinigurai's review is exactly what I came here to write. The levelling up system is insipid, the quests are repetitive and boring, and the plot is a downright snoozefest.
Summary: Save your money. All Zombies Must Die isn't a BAD game, it simply isn't a good one either. As many reviewers have said, it is very repetitive and offers minimal plot development. You can level characters and increase their stats, but the increases are almost indiscernible.