Not that great.
While I admire the effort put into this, it really lacks in quality.
The way you actually play the game is the main problem here.
Taking a DDR style (press x when over specific area according to beat) game and replacing the traditional keyboard control with mouse made it an awkward game to play.
Kinda like trying to replace a concrete bunker with a Styrofoam one and expecting it to withstand bombs. Replacing the keyboard with the mouse in this style of game just doesn't work.
Props for the effort, though.