I got my Wii U as part of a package deal, so I've already got a lot of games: Mario Kart 8, New SMB, SM 3D World, Wii Fit U, Donkey Kong Tropical Freeze, Nintendo Land, Wii Party, Zombie U, and Monster Hunter Tri HD.
All of the Nintendo-developed games look great and play well, probably because they don't try to push the limits of the system, but they still have that appealing "Nintendo look". Zombie U and Monster Hunter just look like generic, last-gen 3D titles. Nothing special. I'm not expecting to see any boundary-pushing games on the Wii U. Nintendo systems have never been about pushing technological boundaries anyway. They're more about novel interaction methods (i.e. gimmicks for Zelda games to make heavy use of ) -- even the original Famicom had a microphone on the second controller.
I do have some criticisms of the individual games, though. As I said, MK8 has no real battle courses -- the battles take place on the regular racing courses, which is not as fun IMO. They really need to add some specially-designed battle arena tracks. Super Mario 3D World is great, but it would be a lot more fun if there were no timer or lives. The levels are so beautiful that you want to take time to explore every nook and cranny of them, but you can't because of the damn time limit. It gets especially frustrating during co-op play, because co-op by nature takes more time so everybody can stay on the screen together. Plus, there's really no point in having lives because, as far as I can tell, there's no real penalty for losing all your lives except that you have to start the current level over again. IMO, these days limited lives just comes off as an antiquated holdover from the quarter-munching arcade days that makes games less fun. Both games are still fun overall, though.
I don't really care about shader unit counts and floating point processing capabilities -- the games are fun, and I think in the end that's what counts. It's also nice to be able to play my old(ish) Wii titles on the system, even though the Wii support feels pretty tacked on.
Another thing that people seem to overlook is the fact that you can play a lot of the games on the controller without even having to use the TV screen. It would have been great if they would figure out how to let you play 3DS games on the big screen, or how to play Wii games without having to use the Wiimote. But still, it's a nice option to be able to play games without monopolizing the TV.
Yikes, this turned into a rant. Sorry about that. Feedback is much welcomed, though.
FWIW, my frustration over the tech capabilities comes down to the practical side effects of them: games running slower than X360/PS3 versions, and not being anywhere near as good looking as any game for the PS4/Xbone that has been developed with those two in mind.
If it was slower but no one was producing games that exceeded Wii U game looks or frame rate, it'd likely be another matter.