Simple but efficient concept, a bit hard at first but once you learn you have to pretty much follow the big circle's opening, it becomes much more manageable
I'm not sure why the UI explaining what the numbers are disappear after a while, they don't take that much space, and after they disappeared I forgot which value was what.
Music beat is pretty simple but works well in that context, so it's nice you took the time to implement it :) Nicely done!