Heh.
Sweet game. Really liked the story, because it was the right difficulty. However, by accident I found an (Awesome!) bug while playing in Survival mode.
I'm not sure -exactly- what happened, but I took damage from a mine/grenade during heavy combat, and my health was below 0. I was therefore capable of massing up a good 400 kills, and could have done as many more as I wished, simply because I would never reach 0 health and die. The quick fix for this would be to just do a search for whether health is above 0 or not.
Also, you should have bloodstains on walls and other results of death fade away after a short time. Even on low quality the game started getting really choppy after 100 kills (yeah, yeah, not many get that far anyway, still something to do though).
Fix bugs, improve story. Make grenade throwing easier. I give you a good 8, for quality gameplay. I'm not one of those people who gives 10 to the first good thing they see! :)