I think the overall look great - vibes so well with the song.
The falling notes are compact enough that I feel like I can mostly fail based on my own skill and not UI issues. The space bar almost never felt good - not sure if that's because I'm not in this genre hardly ever.
My focus needs to be so strongly on the incoming notes that I have no awareness of what's happening with the bowling ball - when I read the idea that I would use any information from the right side to make decisions about the left made me laugh. I think to get that to be realized for the player you'd have to find some way to combine the two sides.