Nice concept
Ilike the way you wanted to have this storyline.
Moreover I like the way you tried to do something else than most of these ddr/ guitarhero look-a-likes on NG.
Still it's not the thing it should have been. Playability is poor, and so are the graphics.
The first few levels only takes de intro riff played correctly to move on.. not really realistic to get a record deal by playing only an intro..
Later onit got way too tough, you have to know the song by heart to actually finish it.. No problem with that but ifyou played that one song for 3 times already, and heard it in the menu too it's way too annoying.
I'd say: keep the concept, make it better, use more songs and improve your art or get another artist to cooperate with.
good luck