I really enjoyed playing the game. Two bugs that kept making me restart (which you can't do so I had to choose a new song) were:
Sometimes it would send two balls at once rather than one then the other, so I would be forced to miss and one of the balls would slowly float off screen while the timer continues at the top.
Sometimes the song would start while my character was walking on screen (not in position to receive yet) and I would miss. Rather than failing the music goes away and the camera slowly moves so I can't see the characters anymore.