I am definitely looking forward to Skyrim, but graphics-wise it's not a huge leap forward from Oblivion. (edit: if the PC version looks pretty much the same, which seems likely).
The shadows make a massive difference, of course, but all games have good shadows these days.
The more detailed (or at least more defined) textures have the negative side-effect of making it very obvious how flat everything is, the cobbled roads look painted-on.
The waterfalls look like sheets, hope the PC version has some extra effects going on to touch them up a bit.
The animations look a lot better, though... and as they have traditionally been one of Bethesda's 'weak points', I'm impressed. The waterfall animation saves them from being super-ugly. Generally everything looks a lot better in motion... which is definitely preferable to the other way round.
The art direction (which is a lot more important than technology any day of the week) is breathtaking, wonderful, staggering. Much bleaker and more imposing than Oblivion, but with splashes of real warmth and humanity.