The game itself is a gigantic hack-and-slash gore fest, where you can freely (and even in the middle of a combo) switch between four different weapons to attack enemies. Much of the party interaction is pretty crass, though, and the main character is certainly someone you wouldn't want to meet in a dark alley. Sure she looks pretty and innocent, but she'll wreck you if she has even the slightest reason for doing so.
Anyway, the "Final Song" portion, which is basically the final boss of the game, is basically one gigantic rhythm game. I don't think it's nearly as bad as the one that was present in the first game, but you're basically countering waves of magic that are sung out by the boss.
Some people have had a very hard time with it, and I don't exactly have the best rhythm abilities, so if we do get a rock-off, I'm hoping that it's more a sequence-memory type of thing.
He're a link: https://www.youtube....h?v=s6w0Q_vh2BI (sorry, don't know how to embed it)
It starts up immediately, and goes for about five and half to six minutes.
And, of course, spoilers, obviously.