Weirdly, I have more Wii titles than I have for either my 360 or my PS3. Maybe my sentimental attachment to certain franchises keeps me from trading in titles even if I don't like them, like the new NiGHTS. Also, for whatever reason, I end up reviewing on Wii somewhat more often, even if it's only 1.5 times more often, than I do for the other two, so I own games I might not have necessarily bought.
At any rate, I guess I hang onto Wii titles more often rather than trading them in because, looking at the ones I have, I might, maybe want to finish playing them or play them some more at some point - whereas I have completed my Xbox 360 and PS3 titles and only keep the ones that I think have replay value (not many).
From these statements, you can deduce that while I generally like many Wii titles, I get sick of most of them before I can complete them. It's the motion control; I'm tired of it. It hardly ever works right. It gets old, fast. I have serious waggle fatigue.
I love Wii for the Virtual Console and for stuff like Galaxy and Metroid Prime 3 and Umbrella Chronicles. You don't get lighter-side, classic experiences like that on the PS3 or 360, where lately everything I've played has been highly detailed, intense and dark, with lots of gray grit, featuring guys who act like jerks and people who are gooey and black.
But unfortunately Wii is the super flavor du jour for the industry at large, which means lots of games forced to be motion games that don't need to be. That, I daresay, should not be. At Kotaku I just investigated rumors that Microsoft is getting on the band-waggle, which I hope they don't end up doing because man alive, I am so sick of flailing around.
Side note -- of the three consoles, Wii is also the easiest to endow with a human personality. It's flanked by the two very tall, very black larger consoles, and there it is all little and white. I know when it is updating because it breathes blue light. It's cute. Sometimes I pat it.