If one complaint drowned out all others among excited Wii U owners on launch day, it was the waiting time to install the system update. Depending on your internet speed and the performance of the Nintendo servers, the download typically seemed to take anything between 45 minutes and three hours, and then you'd have another 10-15 minutes while the update installed. Those who got impatient and killed the power on their system — never do that during an update — or had the misfortune of a power cut, meanwhile, ran the risk of a bricked system.
Life would be so much easier, particularly for impatient people, if you could run the download in the background, right? Well it turns out that you can, it's just that Nintendo didn't tell us.
Recently it was claimed on Reddit that following the right steps would allow you to play games while the system update did its own thing in the background, and fortunately our man Jon Wahlgren just happened to receive his Wii U yesterday. He bravely agreed to try the idea out so that we could make sure it actually worked: after initial setup, he chose "cancel" when the firmware update request came through and decided to play some Nintendo Land instead. After a bit of that he was exploring the system menu when a notification popped up to install the update, which was a short step to complete.
So, performing a background download for Wii U's system update is indeed a simple option if you know what to do, though quite why Nintendo didn't make that clear is anybody's guess. In any case, do not turn off your system, even if you use this method to download in the background while you play some games. It'll be much safer to leave it on until the prompt to install appears, or you can always go to the system update option and manually start the installation once a bit of time has passed.
A "download in the background" button would be nice in future system updates, though.