I'm not sure it's the feature that'll motivate fence-sitters off their palisades to buy one, but if you already own a Wii U -- or better still, two -- the latest system update finally adds the option to run a full system transfer, Wii U to Wii U.
To be clear, you're already able to transfer data off the Wii U, you just can't back it up. Does that sound oxymoronic? Let me explain.
Wii U data can only exist in one place, so you either have it on the Wii U's internal flash or an external USB storage device, but never in both places at once. If you brick your Wii U and your save files live on an external storage device, then you buy or receive a replacement Wii U, you've had no way of recovering those files. Making matters worse, Nintendo doesn't offer cloud saves, so you could argue the Wii U is inferior to the original Nintendo Entertainment System (which in some cases allowed you to save straight to the cartridge) as well as most systems that've come after it.
Nintendo's latest Wii U system update, out yesterday, goes some way toward rectifying this deficit, but the restrictions are pretty onerous. For starters, you'll need the source Wii U alive and kicking and running the same system software version as the destination Wii U. From there, you're in essence running an all-or-nothing clone operation: the source Wii U transfers "any users, Nintendo Network IDs, save data, and digital content" to the target Wii U, then wipes the source Wii U clean.
That's helpful if you own a vanilla Wii U, say, and want to transition to the annual custom-painted limited edition. But we're probably talking about a handful of hardcore Nintendophiles. Who wants to own two otherwise identical Wii Us? And even then, you're not backing anything up, you're just moving it from one system to another.
It's a shame, because what I'd wager Wii U owners really want -- or at least what I do -- is a way to back up those Wii U save files, be it to the cloud or an external storage device. Microsoft and Sony have supported save file duplication to external storage as well as cloud save-file backups for years. Nintendo's system update is arguably helpful for a tiny fraction of Nintendo's audience, in other words, but not the backup/transfer feature Wii U owners have long deserved.