Of all the games I've played, given the choice I would return Monkey Ball, despite reviews I read I still wanted to give it a try but a good example of poorly designed mini game is frisbee golf.
Great idea, golf with frisbees, then you get to the part where you aim where to throw the fisbee and decide the angle of it, the devs pondered and pondered and thought and mulled it over and came up with an arrow stuck in the ground, ah you think tilt the wii-mote ... nope, hmm turn it left and right maybe ... nope, hold on now it's just spinning in circles ... ahh right you aim it at the screen, up for up, down for down, left for left etc, BUT lets make it more fun by not displaying the point your aiming at AT ALL on the screen, that would do wonders for control. It's just really poorly implemented and could with little work (as most of the mini games are) have been much much better with a tiny amount of thought (naughty naughty SEGA). The main game itself though I really really like and think the wii-mote works really well on that, shame it only has 100 levels though
Mini games I did like was Rocket landing, hover race and the equivelant of monkey flying.
Fire up COD3 though and you feel a game well designed with the Wii's controls, all work really well and intuative with clear things on screen to help you if you aren't sure (like melee fighting, but once you get the hang of it I wish you could turn those explanations off).
All in all though I'm really happy and impressed with the launch games.
Monkey Ball I'd avoid and any follow ups I'll rent first as my trust in SEGA has faltered, FPS controls are nice and Wii Play and Wii sports the best way to introduce someone to the machine (boxing is rather fun which suprised me)
P.S Sword fighting isn't done right yet on the Wii, in Zelda or Red Steel, can't wait till devs have more time with it and get it tied down.
And Tree for me Monkey Ball has gone downhill recently, with the N64 one being the pinnicle of it's fun, they messed it up on the GC, then the DS and now the Wii
Oh and ranged combat in Zelda FTW
(And do you still find it odd having sounds coming from the controller ?)