I have just a few complaints.
It's a good game. Solid gameplay, lots of blood and gore...
I can give it all sorts of praise, so I'll just leave it at that.
The background sound got annoying and I didn't see any options to turn it off anywhere.
SO MANY TIMES I got royally screwed on weapons. I kept comping up just 5 or 10 experience short on buying my first weapon at 350...so I'd skip it just to come up 5 or 10 experience short of 500 for the next weapon up..ya know...trying to play smart or something. But no. The game insisted on screwing me.
When you load your game, you go straight into the game. What if you saved it without buying a weapon because you wanted to see if you could hold out just ONE more level before upgrading? Every time you load your game, you're immediately hosed because you don't have the firepower you could've otherwise purchased. When loading, it needs to go to the weapons menu, not the game.
Weapon selection. While it's nice to be able to scroll through, it would be additionaly nice to use the number keys to select a weapon as well. It'd also be nice to change weapon WHILE it's reloading instead of waiting for it to finish. I realize this leaves you with an empty clip in your gun that'll have to be loaded when you switch back, but hey..sometimes desparate times call for desparate measures.
Additionally, it'd be nice to be able to reload without emptying your clip entirely. It'd also be nice for all of your weapons to be reloaded for you at the start of a level instead of having to load them yourself with zombies coming.
Just some thoughts.