Great game
Cool game, I can definitely see the influence from Rez! (Rez was also on the Sega Dreamcast and Ps2 FYI)
A couple things caught my eye that I feel I must point them out. First of all, the backgrounds were good but not great. It would be really sweet if you made them pump to the up beat stuff or maybe even have the ball targets move around. Another thing is if you're doing a game based around music, you should have high quality samples. Low quality will ruin the game basically.
Overall I liked it and played through the whole thing. I approve you to make a sequel if you want. ;)