Not a bad game, per say. But the description really should be more like "Kill as many zombies as you can before you get bored and let yourself die." Because there's really no increase in difficulty as I see it. Except for the fact that some of the zombies spawn, like, on top of you so they're impossible to avoid, even if zigzagging around like a maniac.
It's an ok game, but there's room for improvement.