I think there is something interesting about balancing the dynamic between pressing the right and wrong buttons, and having these two polar actions contribute to a single win condition in a rhythm game. It really capture the feeling of freestyling that comes with rapping. One suggestion I would make is to continue to lean into that concept a bit more, and really showcase it. Highlight the words where the rhyme can change, and maybe make the input button icon glow or something to indicate that the input can be wrong to throw off the rhyme intentionally.
Other than that, I did enjoy the simplicity of the game, and I always appreciate a rhythm game that has the world change around you as you play.