It was a massive success as far as Nintendo's profits are concerned though, it sold massively and reached a lot of markets other game consoles wouldn't have. Plus it had Mario Galaxy!
Honestly, even with Super Mario Galaxy, I don't know how it succeeded so much. It wasn't terrible really, more like terrible in comparison to the actual earnings of it.
It appealed to a lot of new markets though. People who normally wouldn't have played video games but had fun with the motion control and simple gameplay.