I will start by saying that I know these games won't be everybody's cup of tea. Rhythm games are a hard sell at the best of times, and this is a fan service rhythm game with a steep learning curve.
That said, once you get into the swing of it I find it more fun than, say, Hatsune Miku. The Persona 3 and 5 games don't really have a story as such (Persona 4 dancing all night has a 7 to 8 hour story mode, and is included here as a download code,) but have ways of interacting with the characters from those games and learning more about them.
They are fun, challenging games, and if you're a fan of persona they are well worth learning the mechanics of. If you aren't, maybe look elsewhere.