Don't get me wrong, I"m all about gameplay. But I will be irritated if my games don't look any better on Revolution than they did four years ago on Gamecube. I can forgive them for not going all out with the fastest and most expensive tech out there like Sony and MS, but it better be significantly better than Gamecube.
Of course, we know it will be. IBM and ATI are making new chips. If it wasn't going to be any faster they would simply use the chips they've already got and sell the thing for peanuts. Also, as far as I know the Gamecube chip doesn't use the PowerPC architecture. It is an IBM chip, though, so I could be wrong.