Wii U was a weird one in that it had a weak CPU due to using effectively three overclocked Gamecube/Wii cores for the purposes of backwards compatibility, and for some silly reason the hardware prioritised very low power usage despite being a dedicated console, so it was short on raw grunt.
On the flipside, it did alleviate the biggest bottleneck of PS3 and 360 by having more than twice as much RAM, which showed in games like Need for Speed Most Wanted where the Wii U version had better textures than the 7th gen twins.
It was very much a console in the Wii/Yokoi philosophy of "lateral thinking with withered technology", the problem was that unlike the Wii its central hook wasn't appealing to the mass market, and so it fell flat.
You can see with its successor that they pivoted more towards hardware that was quite capable and competitive for its time/form factor.
