Skyrim is based on the Creation engine [its first game actually] and the Havok physics engine. I'll grant it's not as intense as a few other games because they did make some concessions for consoles, but most of those got rectified with the high res texture packs and the Workshop. Nothing about is half-assed, I assure you.
Once again, I assert it's not Crysis 3 level, but few games are or will be for awhile. Crysis remained a top graphical game for 3 years after its release.
The Creation engine is a slap of new paint on the Gamebryo engine. Bethesda recycled it from Oblivion, fiddled with it, and voila Skyrim. Google it.