The real question about the new control gimmick, and yes it is totally a gimmick, is how the consumer base that the Wii built, you know casuals and old people, will take to it.
The whole reason why the Wii was such a success was because it was uncluttered, intuitive, and most of all, CHEAP.
Motion controls were a gimmick that made sense, they were a new way to interact with the game in a natural way. This is just yet another peripheral from a company that is peripheral happy. They even unashamedly featured a video of a blaster gun with the Wii U controller, a Wiimote, and a nunchuck all cobbled together. Seriously?
The controller is also quite large, with a screen and all the other stuff crammed into it is also likely quite heavy. I can't see this as being comfortable for a core gamer who's used to logging in hours at a time as it's as ergonomic as a brick. I can't see casuals getting excited to embrace a new controller that does absolutely nothing to enhance gameplay other than adding another screen they must watch. I don't see the mature market finding a point in the device or willing to fiddle with a wiimote and the controller.
The Wii U will still enjoy sales to early adopters that must have the latest gadget and Nintendo fans salivating at a chance to play a Zelda game with modern graphics, but in the long run I think it's going to scare away the core Wii customers that liked it for it's simplicity and ease of use.
Now all that said. Had the device been a PROPER tablet and be able to transfer and play games anywhere, as well as also possibly running an OS like Android, then it WOULD be revolutionary. As it stands, though, it is just a clunky, large, and likely expensive controller with a non-HD screen.
Ironically with the Ruin demo on the PS Vita they showed that the Vita and PS3 were capable of exactly the same transfer of the game from the TV to the portable, with the added bonus that the game was actually transfered to the portable and could be carried around anywhere, not just within the confines of the room/house the console is set up in.