I Liked It
It was quite enjoyable to play despite being a little short.
Pros
The selecton of weaponry was just right and I died a few times through lack of health, which is good because that means its not to easy, though if I had a second play-through I would be confident I could do it without dying. Graphically it was fantastic, I liked the physics of the zombies falling as well.
Con's
The zombies seemed to be the same throughout, apart from that grenadier zombie if you went through the levels increasing difficulty and making the enemies more varied it would have been better. I also noticed a little glitch when you die using the chainsaw it continues the noise for a while after you die.
Improvements
More varied enemies, perhaps add a flying enemy or two, why not make the soldier enemies shoot, you could also add a whole RPG element to it i.e. increasing skills with weapons, running faster jumping higher, I would replace this with the rampage meter which I barely used.