A follow up. The main problem I have is that the game feels unfair at times. The notes seem to come from off the screen and when switching sides, sometimes there's a note immediately when you don't expect it. Otherwise a really great game that I'm looking forward to!
If you're having trouble reacting to the notes in time, try lowering the scroll speed of the notes! That will give you more time to react, the drawback being notes will become more clumped together. You've got to find that sweet spot that works for you.