okay, so the main story is pretty short. there's also Time Attack mode (with three difficulties) which is essentially a marathon till you run out of time or lives. overall, the game is highly repetitive and isn't worth $4, but hey... was worth trying it (and i had the money anyway, so why not)
To further explain, the game centers around tapping (or pressing buttons; you have to change to them in Options) to the beat, where one is MOVE and the other is TURN (yes, you even have to turn to the beat); if you mistime your hits/presses, the character you play as gets mad (which is actually kinda cute XD). Though the game gets progressively harder, the game just isn't long enough for the cost. There's practically little/no replay value, too. If you plan on getting it, wait till it's offered as a Club Nintendo "end of the year" reward or something; otherwise, I don't recommend getting it at all (unless $4 USD is nothing to you, lol).