Good concept, poor execution...
I think you're on to something good, and this game is certainly well coded, but the art quality, or lack thereof, really brought this down. Work longer on the art of the guy and the planes, and the general layout, and this will be much better.
And different types of planes wouldn't be too much to ask either. You know, faster ones, slower ones, ones that drop loads of bombs in a short amount of time, stuff like that.
Good try, but it needs a lot of work.