The overall mechanics and feel are very nice; of all the rhythm dungeon crawlers I've played, I think this comes closest to what I want from the genre!
The beat timing unfortunately doesn't feel great to me, though? I play a moderate amount of rhythm games and I felt like I was hitting notes on the beat, but the game was giving me fails (and no indication of whether I was fast, slow, double-hitting or whatever). A Necrodancer-style beatbar might have helped with that part, even if only to diagnose whether there's an audio or control lag somewhere?
Still, the concept is sound and the game looks great, so great work!