Tanks is pure awesome. That game is the reason I got a second nunchuk. Worth the price of Wii Play alone. (Played a demo of a similar game on PSN, with more tanks and levels and online play, but without the pointer controls it was difficult and confusing)
I've even seen someone enjoy Fishing and the cow racing game. I'd probably love Laser Hockey if the controls weren't really messed up (When I turn my wrist 45 degrees the paddle should turn 45 degrees, not ninety frickin' degrees). Pool would also be great if there was more than just 9 ball, like maybe 8 ball, the game everyone plays all the time when they have a pool table. But, still worth it for tanks.
"Now, a fun game should always be easy to understand - you should be able to take one look at it and know what you have to do straight away. It should be so well constructed that you can tell at a glance what your goal is and, even if you don’t succeed, you’ll blame yourself rather than the game. Moreover, the people standing around watching the game have also got to be able to enjoy it." - Shiggy
A Koopa's Revenge II gameplay video