Apologises for missing services, too.
Nintendo president Satoru Iwata has apologised to early Wii U adopters for being forced to download a major day one update, and for particular functionality being unavailable at launch.
"I always and strictly tell Nintendo employees never to use the term 'success' to describe our own performance," Iwata told IGN.
"If we call a result of any of our efforts a 'success'... we might apply it as the standard for success for future projects as well, and we could wind up not trying to do better than that or not making something which is very different in nature."
He continued: "So I feel very sorry for the fact that purchasers of Wii U have to experience a network update which takes such a long time, and that there are the services which were not available at the hardware's launch."
One missing feature, Nintendo TVii, is due to launch in Japan early next month and in the UK in early 2013.
Nintendo TVii lets users use the GamePad to display additional information about the television programme they're watching.
Early adopters in the States have complained about the large day one update, with some users bricking their console after powering them off during the installation process.
Nintendo has warned consumers that Wii U's day one system update "could take an hour or more to download and install," and advised that the console "must not be turned off" during the process.
Wii U launches in the UK at midnight tonight.