nintendo have stated the graphics will be on par or better than the competition, remember they have a little long to get the thing together, so they could in theory, take the 360's specs 6months down the road, where there will be an easier/cheaper/less heat making version, as well as the technologies iwata has said about makign it run quieter and faster...
looking at a load of 360 trailers, while very nice, apart from the forest in oblivion, nothing really makes me think 'wow, we really need this now!' its just another upgrade, and i'm sure nintendo will keep check
and for the noobs; forget cube-mapping, you don't knwo what it does, and there will be many more tech's that will be useful