I played Oblivion extensively, and while it was very pretty when you got the huge 4GB texture packs - what was pretty was the landscape, the massive vistas, mountains and valleys. In Oblivion the farther you could see the prettier it was. Almost every random spot in the woods looked exactly like every other random spot in the woods, the only exception being the swampy area in the south, which all looked exactly the same once you got in it.
The Introversion City game is the first piece of procedurally generated content that I've seen that looks amazing. It looks like a legitimate city is being planned out before you. the final result is just like a real city's layout, both planned out, and chaotic. The cities in the tech videos reminded me of Paris.
It is easier to change the specification to fit the program than vice versa.