Would have given a higher score
This game is awesome, my only problem is that the screen feels very crowded, sometimes it's impossible to move without hitting a bullet, missile or other aircraft, and I thought the health pick-ups gave too little a health boots. An "extra life" pick-up would allevciate this, however. I also agree with the other guy in thta it was annoying that every weapon was fired at once, perhaps you could have A,S,F,D for each weapon.
What I think you should do next is make this one of those complete level, gain points, buy upgrades sort of game, as well as moving up the ranks like you do in this game.