What most of us mean when we say a game is "pretty," or "looks amazing," is that it had a great designer. Whoever conceived of the things the graphics engine is modeling knew how to impress human beings, and it wasn't with sheer pixel count or dynamic sand integration: it was through setpieces. Skyrim wasn't graphically the best-looking game, but it had moments where the player would stumble onto a setpiece somewhere in the open world -- a mountain path framed so that the player came upon a dramatic overlook just as the aurora flared into life; a snowstorm that raged into existence just as a dragon launched from its cliffside perch; a beautiful sunrise just as your horse glitched into an eternal backflip and sent you clipping into the nether-dimension between mountains -- and it took your breath away. I'm not arguing that Skyrim was the prettiest game or anything (for my money, nothing's ever beaten Okami), it's just the latest, most prominent benchmark in design over raw computing power.
"But how can you say that? Look at the v's flying around, willy-nilly! It's hideous!"
Far Cry 3 is beautiful -- it's a technical marvel -- but the islands it takes place on feel empty and flat. They're neither of those things, of course: It's a densely-packed world, and the terrain does vary, but you get the feeling it all could've been randomly generated by a computer. There's no sense of place, as there is in less-impressive, but better-designed, worlds. You don't intrinsically understand a road or where it leads just by walking down it. Amanaki Village, the game's "hometown," is no Whiterun, and Rook Islands are no Liberty City. The world of Far Cry 3 is not technically inferior in any way, but it lacks cohesion and grandeur. You don't build a mental map of it like you would your own neighborhood, and you don't stop to marvel at the crumbling jungle temples or stepped waterfalls. Oh, sure, you'll memorize where things are, but that's familiarity, not intimacy. In short: you can build many houses out of the bones of the sharks you've hit with your jet ski, but it will never feel like home.