I shall write my feedback here since the form is broken. what I like has already been said or thought of so I will instead add a new problem. the building mechanic is in its entirety broken.
1) zombies clip through any construction
2)you can only have your walls on one axis
3) While you're on a ramp or any non-ground/floor object (like a ramp) the game thinks you're falling, increasing your velocity and stopping you from jumping. Pirate Software made a video on this
4)The icons are... well I shant comment on them
also a non-building problem
5) the weapons can get switched around. if you switch weapons commonly, slot 2 can be for every weapon. I'd prefer it if each weapon had an individual button to pull it out.
Other than that, Its amazing