It will be better than the current consoles. It would be a real shame if it isn't stronger than the XBOX 360, PS3 and especially the Wii.
Also, good games are the ones that makes the console powerful not much of the Specs. Look at the Gamecube, it had great games which made it way better that the PS2 and XBOX . If the Wii U will release excellent games, it will be f*cking better than the XBOX 360, PS3 and Wii.
Gamecube totally destroyed the PS2 in raw power output, PS2 had a better library however.
A better library indeed, no matter which one you preferred.
While the Wii U could be the next-gen underdog (although no were near how the Wii was) there are many other factors other than power that attracts third parties.
The PS2 for example was not as powerful as the competing systems but it still got great third party support, that is because it was cheap, doubled as a DVD, had USB support, had games like the EyeToy, it was easy to pirate games for and lastly, it had backwards compatibility.
The Wii U has the potential to improve in many areas for the mainstream gamer, not only in the graphics department.
If the Wii had hardware and online comparable to the other current-gen systems it could have been a second PS2 in terms of developer support.
More power does not automatically bring more developers.
Remember that developing costs are going to be incredibly high next-gen, that is for games that actually will take full advantage of these systems.
That said the Wii U still has to be a at least a half-step above PS360, something that I don't doubt it will be or surpass considering the newer tech involved.