The Wii U is Gamecube 2.0, honestly. Nintendo's problem was that they mistook the Wii's success as them gaining a new core following of gamers, not seeing it as the casual fad it really was.
That led to Nintendo releasing a core-focused console with the Wii name and thinking it would somehow catch on by merits of being a "Wii" product.
3rd parties never fell for this, they understood that Nintendo consoles do not more 3rd party software to core gamers. This is why Nintendo can't get 3rd party support.
The Wii U will wind up as a quality system to own because just like the Gamecube Nintendo's first party lineup will be excellent and they'll bring enough non-Nintendo IPs to the party like they're doing with Bayonetta.
They've committed the same mistake with the 3DS. They mistook the NDS' runaway success as a product of their brand and hardware innovation to dual screens, forgetting that it's biggest selling point was lots of compelling software at a very friendly price.
If the 3DS was instead just the DS2 and lacked the 3D features no one would miss it and Nintendo could sell the system for significantly less, likely picking up right where the DS left off. They added meaningless hardware with no angle to sell it, and are suffering as a result.
The Wii U's tablet is the same thing. It sounds like a good idea in the vaguest of senses, but you've got to show us why it's worth paying for.