After a couple of levels, this is what I noticed.
The placement of the "Power up" to fire is pretty awkward in the early levels. It was pretty difficult.
Also, I don't know if this is something that was mentioned previously but it doesn't work on Safari MAC OS- wasn't moving past the loading screen.
It would be nice if it told you what level you were up to on top of the screen.
I'm looking forward to seeing your further development of the game. Overall it's fun!