Wii Music is essential if you have any interest in the drums; the balance board drums mode is incredibly well put together, and by far the best drum simulation on the market.
Contrary to the dumbing-down in Rock Band, which just gives you four colored drums and one pedal to hit DDR style, Wii Music's virtual drumset is exactly like a real one: 2 cymbals, 3 toms, snare, hi-hat opened/closed by your left foot and bass drum controlled with your right foot. On top of that, you can choose from 4 different drumsets, including a jazz set played with brushes. The lessons included walk you through the real basics of drumming, from basic 8-beat patterns to simple variations and fills. You can then, of course, drum over any of the included songs, playing whatever beats and patterns you want, then save a video or start overdubbing all the other instruments.
The sensitivity is such that you can give the drums anything from a light tap or a hard hit, and you can learn to play anything you could play on a real set, but without driving your neighbors crazy or needing to invest in an expensive kit.
If you want to see someone play it well, check this out, or any of this guy's videos (this is not me, I'm not nearly that good yet):
