I've seen plenty of games like this one, however they had a bit more to offer, this. Well it offers this:
The graphics and the ships were great! So was the speed, kept me on the edge of my seat, looking at my ammo and trying to use it carefuly. Moving to the left, right, and dodgeing the suicidal plane/ships was fun for a little while.
The power ups hardly ever helped, and ammo never showed up when it was needed, only when I had 100 and it popped up and said "Hey! You don't need me! So I'm here!" and that was a bit ball busting. If you get far enough its just doing the same thing by looking at the ships and how they move, where to move to hide and where to come out shooting. So it was repeditive.
Work on it.
There are plenty of games like these and to fully commit yourself to these games and make a better one takes time, not just fast movement, breakneck gaming that gets boring fast. May want to work on the powerups and slow things down a bit, not to much, but a bit. The ammo concept was fine, kept you looking up and your eyes moving to make sure you had enough to live, but at least put more ammo drops in there.