Take Parappa the Rapper, remove everything good about it, and you'll have something close to Mad Maestro.
Gameplay:
Think Parappa going in a circle. Very boring. The whole game is really just watching the little dots fly around and pressing the controller at the right time. Oh, but it dosen't end there. The game gauges how hard you press the button, so you'll find yourself failing what should be easy because only the daintiest touch will work on some notes.
Graphics:
Not too good. These could easily have been high-end PS1 graphics.
Sound:
Classical music. Ugh.
Value:
If you could get past the terrible controls, you might have a decent rythm game. Only problem is, you won't.