There's nothing wrong with the game at all.
Everything was actually pretty perfect. It did not scroll too fast, the amount of power to kill the enemies made it challenging for the player. The controls were what they were, and everything was fairly clear and the controls were smooth and easy. The gameplay was pretty clean cut.
It was mainly the art that really brought this down a lot, sorry to say. The background was too plain, the characters were too simple. Things weren't drawn as well as they could be, so that definitely took away from the value of the game.
All in all it was an okay game, an idea done many times, executed fairly well, very unprofessional feeling, but worth a look.
Honest review =]