Honestly, it's hard to put the game down and with a lot of game modes you'll have an even harder time not coming back.
Let me start out by saying that it will take a few minutes and a few tries to understand on how to play this game. I'd recommend starting out in the minigolf game first, just to get a feel for it. After that, I'd go for either unlocking characters or tournaments, either way, it's a blast!
The gameplay has a lot of depth, a surprising amount of depth, actually. It is really makes the game fun to master with a surprising amount of things to consider when taking a shot. If you get bored of the normal game, then there's minigolf, ring shots, and speed shots. It's all good. Replays are awesome too!!
So, if you're on the fence about this, then I would get this game, it would be unlikely that you'd look back. You can also get it for only $10 on the Wii right now, so it's a great deal considering the amount of depth, re-playability, goofyness of characters and competitiveness this game comes with!