Really high levels of polish, but the fact that you cannot play songs at all if your case slots are full is unbelievably stupid. Considering how expensive buying songs is compared to other rhythm games, and how you don't even get to pick the songs you purchase with full confidence, there is absolutely no reason to spend any money on this game whatsoever if the game actively forces you to pay more money to open case slots so you can play songs you've ALREADY PAID FOR. This ONE thing needs to go