It's fun, I like the mechanic of having to attack to the rhythm, but yeah it's pretty tough to keep track of both the rhythm and the boss. I think having the entire rhythm circle spin win you is probably the most disorienting thing, maybe having the rhythm wheel separate from the player and not rotating with them would alleviate that.
On another note the music is well picked, I like how each boss is themed around a different music genre, reminds me of No Straight Roads in that regard. Nice work :)