First of all, I love the game. It has some great potential. I mean it. The bleeding and bandages, the S.O.S drops, the stealth, it's fantastic. There are a few notes I would suggest though. The first and foremost are mainly glitches I'm sure you're working on such as the server instability, the guns firing after they reload, and the zombies that get stuck on walls. These are more than forgivable due to the depth of gameplay and fun features. My only suggestions would be an ability to configure controls, maybe an easier way to drop items, and some more character customization.
Seriously, I don't remember the last time a concept game like this made me smile with the detail you've put into this gameplay. I'm impressed.