It is a well-made game and has all the basics down, but it's something we've seen very, very often. Shoot these guys, you're done the level, buy new things or repair stuff, and go to the next level and so forth... though it is well-done, it's sort of a cliche game. Kind of a "Poor idea, great execution" type of thing instead of it being in reverse order... which honestly isn't bad.
I noticed the shooting lacked a feel of power... I don't know, it's a tad hard to describe. When you shot, there seemed to be no recoil and the sound effects were kind of low-quality sounding. At this point, some may consider that I am nitpicking, but if you're going to make another Flash shooter like this, you have to offer things that others do not in order to set it apart, not just make a clone.
However, the drawings and background look very, very nice... the soldiers were well-animated as well. Seeing a ton of weapons to buy is always fun, too, since it gets the player to think "woah, I want that!! I have to keep playing to get that much money!" and it keeps them going.
Though it's decently-developed with minimal amounts of glitches, and it seems to work, I didn't find it very fun. I guess it's a good time-passer, but it really isn't much else.
Nice job, though, you are better than I am at making games. I would look forward to any other things you have planned in the future, just think of a unique idea next time.