With a few more improvements, this could be good.
This game is addicting as much as it has room to improve.
First off, this game reminded me of Dance Dance Revolution so I think you should adopt a similar gameplay style (you gain life by destroying targets (more life if hit in areas like the bullseye) and loose life when a target exits the screen.) There should also be a combo counter counting how many targets hit in a row. Graphics can afford to be better and there could be more of an animation in the background that looks like it follows a music video.
Other than that, this game has potential. I'd like to see an update sometime.