During an interview series with Earthbound / Mother creator Shigesato Itoi, Iwata made his point very clear:

Itoi: Everyone thinks Wii is such a success, but Nintendo hasn’t become overproud of it. Actually, I don’t think I ever heard you say "Wii is a success."

Iwata: Not yet.p[…] We want to have the customers continue playing. We want to continue coming up with new proposals to them, and have them keep playing. Only then can we say that we’ve accomplished our goals.”

Later on, he continued: “We need to see if our new approaches will grab the customer’s hearts, if they will keep on playing our games. The answer’s not out yet, but I believe we’re getting there.”

Recently, the Nintendo Wii took the title of “best sold next-gen console” from Microsoft’s Xbox 360, in spite of the fact that the latter had been launched one year earlier.