Actually, Iwata has said the graphical quality with be indifferent from a 360 on a non HD TV.
Since they also say that on paper, it looks as though it will have a lot worse graphics than the others, the only thing that could be up is that they are using new graphical technology which uses less power.
And yes, I can tell you that the PS3 uses more power for polygons (duh) and Reggie has stated that the PS3 has a frame rate about 3X more than is needed.