Very cool, and the theme implementation has actually reached the perfection in this title!
I just would love to see the feature where the boss actually hit(/throw?) his own ball from the same place where the player does before the player does: Then the needed distance value varies on each game a small amount and the boss play with the player. Of course the boss is very good player, and avoid throwing the ball off from the edge, though.
The menu graphics and other graphics would be a little better, but this is great. Boss with a silly huge crown make it just right annoying to want to competitive with him and win any types or any amount of the levels just to beat his score on it's kinda like "own game".