Yeah, Wii sports does indeed pwn major ass...
The game was able to hook my mother (who has never played a game since the NES), both my nephew and niece, my sister and my brother in law. And I am personally in love with it too. My favorites are definitely bowling and baseball (even though I can't do a homerun for the life of me...). Golf would have to be my least favorite because the controls aren't all that great.
My main fear is that the game's appeal could end up not lasting as long as people expect it to. See, the game is a blast when it you show it to a lot of people, especially people oblivious to the concept of the game. But it starts to lose its appeal once you keep playing with the same people. I think at one point they will want to see something else, something new. Wii sports gives them a huge taste, and they will definitely want more and I doubt they would return to the same game over and over.
But outside that, Wii sports is easily the biggest surprise of the game because a lot of people were disappointed that the game was making the Wii more expensive and now they can't get enough of it.