The rumours that have come out about the Wii U's hardware are vague and (often) contradictory, and it is likely we won’t have a decent idea of what it is really capable of until after E3.
The early suggestion of a multi-core IBM CPU and a GPU based on ATI’s R700 seemed entirely reasonable. Being that this hardware is hardly new, Nintendo would (likely) optimize and customize the hardware increasing the performance while reducing the cost and energy consumption, and this hardware would have been in the range of 4 times the power of the HD consoles when it was initially released, if Nintendo went this route I highly doubt that the Wii U would be that similar to the performance of either HD console.
With that said, I highly doubt people will really see a "generational" jump in performance from any console in the next generation. Between the diminishing returns of hardware performance, the massive budget required to make games to take advantage of it, and the high costs associated with the HD consoles at launch I don't think anyone is going to repeat the strategy of the HD consoles this generation; after all, who would want to buy a $600+ console with $70+ games ...








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