Polygon reviewed the Nintendo's Wii U and have come out particularly disappointed with the new tablet controller. Most interestingly, it uses resistive touchscreen not allowing for multitouch input, and the battery is extremely lacking.
In the past resistive touchscreens have been favoured when accuracy is needed for single point touches, its advantage over capacitive touchscreens like on the iPad. However in Nintendo's case the input feels inaccurate and requires too much force to register.
The battery's 3 hour playtime is also considerably weaker than competing tablets, and may end up seeing the controller perennially plugged in. I imagine these hardware choices were made in favour of cost reduction, but it makes it hard for consumers to take the Wii U tablet experience seriously in an arena dominated by more robust tablets.