Although you don't get the feedback sensation that is integral to playing the drums, it does have the advantage of having a full virtual drum kit rather than relying upon a controller that is a very rough model of a drum kit.
While I can't say anything positive about the music selection that will undoubtedly be included (I have no desire to pretend to play along to Nintendo theme music), I will say the virtual drum kit alone almost make this worth a buy.
Unfortunately, without accompanying music of your choice, playing virtual drums is more of a solo affair. Now if it allowed you to play along to user ripped MP3s, that would be a real winner. The drum tutorial sounds interesting, particularly if it goes beyond the basics.
The rest of Wii Music does seem a bit pointless though. Pantomiming with virtual instruments via random button presses and motions to activate pre-sequenced notes? No rhythm required although at least it should allow for improv pantomiming.