Taking everything into account we're looking at a console around 4 times more powerful than the 360 which is pretty much a traditional leap in power from one gen to the next....
We've had nothing but rumours, as is usually the case with Nintendo, and it's impossible to do a direct comparison and say a console is "x" times as powerful as another - but around half the rumours seem to put it at about three times as powerful as the 360, and half the rumours have it about equal with the 360.
I'd imagine both are right, with some elements three times as powerful and some only on a par. And that's a woeful increase in anyone's eyes but Harv's. They've had about seven years to come up with a contender for the next gen crown, and they've come up with something that only just shades the current gen.
Not sure where you get the impression each gen is usually around four times as powerful as the last. I'm pretty sure that most benchmarks have each gen at significantly more than ten times as powerful as the last. And that's when they have around 3 or 4 years to come up with a new gen - this time we've had double that, and could arguably expect to leap forward the equivalent of two generations.
Now I'm not saying the next consoles from Sony and Microsoft will be a hundred times as powerful as their current ones - but they'll surely blow the Nintendo machine out of the water.
As for motion control - I really don't like it, but I can't say whether it's a deciding factor for me at this time - because there's a high probability that all three consoles will have it in one form or another. Hopefully they'll not be the norm on the Sony/Microsoft machines, though, but again we can only speculate at this point...