Romier - I was playing a rented SMB, with no instructions. The Target game was infuriating initially. I started getting the hang of it later, but it never grabbed me like the others. I found boxing to be the most fun :)
I was surprised, though, that the single player game didn't amuse me as...
Though I didn't find Monkey Ball particularly interesting (when I played it over Christmas), the two mini-games Monkey Fighting and Monkey Race are just about worth the cost of the game! They are really fun.