In cpu terms the wii u is ridiculously under-powered for its release date. Most wii u games that are also available for ps3 and 360 perform weaker on wii u with the only exceptions being 2D games and light cpu games like racing games. Also the gamepad is a terrible controller, bulky and missing analogue triggers. Not only that but the launch price was ridiculously high for such a weak console.
Instead of a gpu with 176-352 gflops performance they needed something like 700 gflops and instead of 3 incredibly weak 32bit 1.25ghz powerpc cpu's it needed perhaps 4 jaguar cores (or the early version I forget the name of) which would easily have been up to the job of emulating the original wii powerpc chip at full speed.
The controller should have been a conventional joypad design that also doubled as a motion controller.
Personally I think it should have been a top loader design for the disc so it could run gamecube and wii discs.
There are lots of other things I would have done differently but the meat of it is a console that sits in the middle between ps3/360 and ps4/xbone not stuck with the 360/PS3 in performance terms.
