I can't believe this is even a question somebody could seriously ask :). The metrics are so simple and obvious I can't see how you can miss it.
1. Did it sell better than it's competitors? YES
2. Did it make a profit for its company? YES, from *day one*
3. Does it have a library with enough great titles to make it worth owning? YES
4. Did it do something new to the gaming industry? YES
Whether it met the needs or desires of every last person is irrelevant; NOTHING meets everyone's needs or wants, that's why there's a market for more than one approach and one product :).
Wii is, by every reasonable standard, a success.