Sunday was the big launch day for Nintendo's Wii U game consoles. But already users are complaining that they are experiencing long waits for mandatory software updates and that some of the device's most notable features, including the company's social network, called Miiverse, are not working.

What's more, Ninentdo said that some of its video features, such as Amazon Instant Video, TVii and Hulu Plus would not be available until later.

"So many Miis have jumped on Miiverse that some may be having problems connecting to the service," said a tweet from Nintendo shortly after its new console hit store shelves. "We are in the engine room getting it fixed!"

The Wii U is Nintendo's first console since its hugely popular Wii was released in 2006.

The Wii U builds on its motion-controlled predecessor with more powerful hardware, support for high-definition video output, and a novel tablet-syle controller featuring an integrated touch-screen display. Demand for the console has been high, with many stores across the country reporting empty stock.

Those lucky enough to have got their hands on the product are reporting multiple issues such as a necessary firmware update to fix bugs and enable online multiplayer modes that requires a huge download that can take more than two hours.

"Every single game requires about a 200 meg update to function with Miiverse," said one review on Amazon.com.

"Download speeds from Nintendo's servers are awful. The very first thing you need to do is download a system update that's well over 1 gig in size. It took me 2.5 hours to get it. After that every single game you play requires an update."

However, other reviewers were more philosophical, saying that the launch-day problems should eventually be ironed out by Nintendo.

"You may want to bring a book along (at least at first)--the initial setup required two downloads to be made over the internet," said a person who bought the console on the day it was released. "This is most likely going to be an early adopter problem--I suspect since today is the release date that Nintendo's servers are getting slammed."

The Wii U is available as a $300 basic version, with 8GB storage and a $350 deluxe version that comes with 32GB storage. The console has been released with a strong lineup of titles including New Super Mario Bros. Mii, Darksiders II, DiRT, Aliens Colonial Marines, Tom Clancy's Ghost Recon Online, Metro Last Light and Tekken.