Y'know, I'd kind of like to play Bayonetta 2. But other than that, I really have absolutely no reason to buy a Wii-U right now.
Understand, I have a Wii and a pretty good game-capable PC. On the Wii, I still have all the Dance Dance Revolution games, the Rock Band games, ports like Okami and Gamecube offerings like Eternal Darkness, the latter two of which haven't even managed to crack my limited time allotment for gaming despite by all rights being quite excellent.
On the PC, I have the back-up in my Steam Library, plus most of the better AAA-games coming down the line sooner or later, a tide of indie offerings, and the increasingly agonizing excess of the Humble Bundles.
I also have a DSi, and access to a 3DS if I'm willing to pry it away from my daughter. And even Nintendo seems remarkably willing to pour their development time and energy into the 3DS rather than the Wii-U.
So... Why the Wii-U? I'm sure it's a perfectly fine machine, the demos I saw of Rayman looked enjoyable enough, but there's little there to lure me away from my alternatives. And perhaps most importantly, they really haven't succeeded in establishing the GamePad as a must-have offering unexplored means of enjoying games. Rather, it seems like a gimmick that ends up uncomfortably shoehorned in, mostly into ports that worked just fine without it.
When Nintendo figures out what the GamePad is good for (asymmetrical multi-player experiences, hello...?) and gets some third-party publishers more involved, I think they have a good chance to catch up. But right now, they're definitely playing catch-up.