I received Boom Blox as a birthday present the other week. It's a fun game, except that the Wii can barely run it on some levels. The frame rate gets killed and the system sounds like it's going to die from exhaustion.
The Wii itself has been so unreliable for me. It often has trouble simply booting games. Other times, the games will boot, but the load times will be out of wack. When I first played the new Mario Kart, I thought I was playing a Sega CD game with the long load times. After taking the game out and restarting, it played fine. I just read that the system is prone to problems with dust, but I'm fastidious about keeping my stuff clean. Weaksauce.