Hard But Rewarding
This has got to be one of the hardest Flash games I've ever played. Despite the difficulty, I found it to be very enjoyable. There are a few points I don't like, but a lot of points I do like.
The game seems to lag horribly, which is the main thing that lost the game a few points. If the frame rate remained constant, the game would be a 10/10. The things I liked are the fact you put recoil and such in the weapons, and there are so many different campaigns to pick from and play.
Maybe make the game more accessible to newer / crappier players (such as myself) and add more missions to make it longer. Either way, it's still a great game.