the best i can compare it to is if Pokemon Mystery Dungeon married Binding of Isaac and their kid was raised by wolves that listened to techno or something
each run is randomly generated, so there's no telling what you'll get each time you play. i find the music to be the highlight of the game, but i probably wouldn't recommend it if you aren't the best with rhythm games. if you can hold a constant beat at various tempos then you'll be fine, there's no fancy rhythm heaven level shit, but there are times where the tempo will temporarily speed up or slow down, and plus there's the added stress of having to learn and predict enemy patterns while still maintaining that beat.
you will die a lot, it's not an easy game by any means. i wish there was a demo or something because that would probably be the best way to tell you whether its a game for you. maybe watch some gameplay on youtube if you haven't already.
in saying that, the character designs, style and music are absolutely tops. it is also really cheap right now so you've only got a few dollars to lose if you really don't like it
also i'm not sure what you mean specifically by 'necro-sounding game' but it does have skeletons and the story revolves around a woman whose soul is damned by a crazed warlock to dance for eternity as she searches for her lost father if that's any help