I guess there wasn't anything that bad about it. The main problem is that it's too repetitive. It's just the same enemies over and over. I don't know much about the original to compare it to. I think it was just too basic. At least it wasn't that hard or anything.
I would have liked an upgrade that got rid of the enemies faster. It was at least interesting to see something different. I couldn't really notice the songs on this. Then again, I wasn't into the game that much.