The Wii-U is simply not a good value compared to the PS3, much less the PS4 which is $50 more.
Wii-U = $300~350
PS3 = $250~300
They have roughly the same CPU/GPU performance, but considering the PS3 is 8 year old technology... doesn't make the Wii-U that impressive. Especially considering the price-point. Yes, it means Nintendo's Mario games can look spectacular... but... where are they and why not just port them to other consoles?
Other issues with the WiiU: For a $300 device, it CAN'T play Blu-Ray, hell - it won't even play DVDs. (US version of Wii doesn't play DVDs either) This would be very handy when putting the device in a kids room. The PS3 plays Blu-Ray of course. What size HD does the Wii-U have, oh none. Either 8 or 32GB flash memory Not impressive compared to the 250~500GB drives on Xbox and PS3-4.
The tablet is causing more problems than its solving. They should have kept the Wii standard controls. It ads a lot of cost and bulk to the system, yes it creates some new game styles - but its now more complicated. Making an APP for Android/iOS that talks to the WiiU would have made more sense and reduce the price down to $250, tops.
The Wii-U was designed to attract the PS3/360 crowd... who already have the same teach... who are wanting the PS4 today. Being 8 years behind is not good.
If Nintendo was SMART, the Wii2 (my name for it), should have come out 2-3 years ago, have a GPU that is twice that of the PS3/360, standard Wii controller, DVD only (since they aren't playing Blu-Ray) and sell it for $250 (with 16GB flash).
PS: oh, I am guessing that the Wii-U is using left-over HD-DVD drives / tech.. bought them for a steal. Makes it much harder to pirate a dead format.