How much more powerful do you think the Wii U is compared to PS3/Xbox360.

[HappySqurriel]

I think a raw number may not do justice to what the Wii U represents ...

One of the more important concepts in modern game engine design is scalability because publishers want to be able to release a game across as many platforms as possible and developers don't want to create an entire set of models and textures for each platform they release a game on.

(Probably) the most important technology related to this is tessellation which will allow a game engine to render an object at lower detail when it is on lesser hardware or the detail wouldn't be noticed, and then to increase the detail on better hardware when the increased detail will be noticed.

While the XBox 360 and PS3 can not receive the full benefits of this, game developers will (potentially) start producing games where the base level of detail is somewhere between what you'd expect from an XBox and an XBox 360 game, and then (through tessellation and displacement maps) the detail level can be increased far beyond what we've seen on the HD consoles.

The net effect of this is that, even with rendering the same number of polygons, the Wii U version may appear to have more detail than what we've seen on the HD consoles so far.

With that said, I suspect the Wii U is probably 3 to 4 times as powerful as the HD consoles; and when you see cross plaform games produced with game engines that are designed to scale being released on both the HD consoles and the Wii U there will be a significant improvement in the visuals of the Wii U version.