As confirmed by other reports around the globe, the new Wii U requires a 5GB update from Nintendo to enable all online features. But, unlike the PS3 and Xbox 360 that roll back changes if an update fails or the console shuts off, the Wii U will become a giant, shiny, useless brick if you switch it off while the patch is installing – nothing happens, of course, while you’re downloading the update. So you have two options:
1) Update the console and cordon off the area with Police tape and tell everyone you’ll hit them on the head with the bricked console if someone causes the update to fail.
2) Don’t play online at all or update the console until you can safely do so (see, 1). Wait until Nintendo has the common sense to offer this as available to download on a desktop, transfer it to a flash drive and then update from a local source.