Parents have nothing to be cautious of here. No violence, no nudity or sexual situations, and no questionable language whatsoever. Your kids will probably play this boring, shallow game for a total of seven minutes, but it will be a risk-free seven minutes, without any fear of problematic material.
Music gamers should look elsewhere unless they absolutely need to own every single title in the genre. You can "finish" the game in your first sitting, and there's little incentive for repeat performances unless you enjoy doing the same shallow, simplistic thing over and over. It's got a bargain price, but in this case, you get even less than what you pay for.
Deaf and Hard of Hearing gamers: I doubt you're even considering this game at all, but if you are, don't. The game is bad enough as it is, but without hearing the music, all you're left with is moving a moppet around a bunch of circles and looking at the pretty colors. On the plus side, there's text for everything, and it is possible to play the game through visual cues alone. I don't know why you'd want to, but you could.