Neat game. Would be cool if once you beat a level you could get the 'solution' which would make the level sound decent, instead of the cacophony of noise that you get if you beat the level by 'accident'.
I think the most irritating thing about this game is dying while you are "leveling up". You shouldn't explode when you are airborne, if you run out of fuel during a 50 kill combo, you shouldn't be penalized. Also, if you get enough experience for the next level, you shouldn't explode waiting for your experience bar to count up the points.