I think it has awesome mechanics, but it lacks in certain aspects:
Fighting with your hands is fun, but adding weapons is even better(let's say you can find them, but they break)!
It would be cool if you could upgrade you character for exp points.
Add some stronger and faster enemies... sure it's zombie rampage, but little bit of variety can never hurt.
Also - fist punch sucks big time. I think using only kick, then just waiting for stamina to be restored was the best way to stay alive.
But then it ruins the paste of game - become too slow...
Add all things I've mentioned, a story line (even if it's a cheesy zombie one) and it could become one of the greatest games on NG.