The clever chaps down at the Digital Foundry have found the Wii U is a rather efficient piece of kit. In terms of performance per watt the Wii U is the clear winner, providing an equivalent graphical and gameplay experience to the tree killing Xbox 360 and Playstation 3 all whilst using less than half the power consumed by the other consoles.
When examining whether the Wii U will do what the Xbox 360 did and, y'know, Red Ring itself to death for epic performance (I'm not talking about erotic asphyxiation). So don't expect to have a heavy drug gaming session and wake up to find her the Wii U dead like I have experience on many occasions.
However not everything is fantastic and magical. To quote the article;
"The Wii U's lack of CPU power compared to the Xbox 360 and PS3 is a topic that's been covered extensively before, but the main takeaway here is that a CPU running at just 1.24GHz and using far fewer transistors than the competition (the physical size of the chip is much smaller than both Xenon and Cell) is obviously going to consume far less power than its rivals (Leadbetter: 2010)."
The best analogy I can think of is being able to produce more sperm but at the price of having a smaller penis.
Overall whilst it seems the Wii U isn't a huge leap ahead regarding power, it does like look a well built piece of tech. Like meeting a girl who is kind, thoughtful and generous but she has small breasts and you have to get home by 11.