You can transfer most Wii data to a new Wii U. This is a good thing, but nearly as good a thing as the animation that plays when you do this. As soon as it started, I had to grab my camera and start shooting this.
The first video shows what you see from the Wii when the data is being transferred from Nintendo's 2006 console to an SD card. (Skip to the final minute if you're pressed for time!)
The second video here shows what plays on the Wii U when the data is being moved from an SD card to Nintendo's new 2012 console.
You can only transfer data from a Wii to a Wii U once. After you do, the data is gone from the Wii.
To begin the process, you go to the Wii U's Wii application, which shuts off the new console's GamePad and basically turns Nintendo's 2012 console into its 2006 one. This is my Wii U as a Wii:
You need your Wii, your Wii U and an SD card with at least 512MB of free data (it can have other stuff on it). You'll want to have two Wii Remotes, one to drive each console, but you can do it with one. Both consoles will need to do a check with Nintendo's online servers.
This is what will transfer:
This is what won't:
Sadly, you also have to say goodbye to the Mii Parade, the procession of Miis pulled from other online systems. It was one of the coolest features on the Wii:
First, you put the SD card in the Wii U and run a transfer tool from the machine's Wii app. Then you put that card in the Wii and run the Wii's version of that app. (You download these apps from the Wii's online store, which is accessible from each machine—curiously the Wii U isn't going to the Wii U eShop which suggests that Nintendo will have to keep the Wii Shop live for Wii U owners who use the system in its Wii mode). The Wii starts moving its data to the SD card, which is when the animations in the first video here play.
Then you put the card back in the Wii U and the animations from the second video play.
And then... you're done.
You can see how long it took.
While you're transferring, the Wii tells you what it won't be bringing over. Nothing that used Wii Connect 24 makes it over. No Everybody Votes channel, no Nintendo Channel. The game Lost Winds wouldn't transfer either, for some reason. Saves move over. Downloaded games do. Miis do. Your purchase history does, so you can re-download things to the Wii U's Wii app.
The system all works smoothly, but it's bizarre to see how walled off this stuff is. The Wii experience in the Wii U is isolated from the rest of the system. The GamePad can't even drive it. That raises questions about whether virtual console content downloaded to the Wii will ever be accessible on the Wii U's main menus or whether it will always require the cumbersome extra step of loading the Wii app. Considering that the GamePad is deactivated while the Wii U is in Wii mode, it's no wonder that Nintendo has said that Virtual Console games can't play on the GamePad. That's too bad. Hopefully they can at least support the Wii mode on the GamePad in the future.
For now, though, the transfer seems to work well. And it's just so darn cute.