Pretty good.
I liked the graphics and the game in general. I would definitely play a sequel, or perhaps a longer version of the game.
The one enemy's fighting pattern was uncannily similar to the first boss in the flash version of 'alien hominid.' Was that intentional?
One minor issue was that bullets would move farther if you walked along with them, which actually works to your advantage at times.
(I switched my rating from 8 to 10 just now when I read that all the ad revenue was for breast cancer research. Good luck with that.)