Yup, as always it comes down to the games.
The 3DS has:
- Super Mario 3D Land
- Mario Kart 7
- New Super Mario Bros. 2
- The Legend of Zelda: Ocarina of Time 3D
- Kid Icarus Uprising
- Resident Evil: Revelations
- Paper Mario: Sticker Star
- Mario Tennis Open
- Kingdom Hearts 3D
- Lots of fucking games that I can't remember
The Wii U has:
- New Super Mario Bros U
- Nintendo Land
- Zombie U
- Some games that are available on other systems
It's a clear case. The Wii U is screwed for the time being. Not to mention that the other HD consoles and the much cheaper Wii console are competing with it as well.