Sometimes I just stop and stare at it for a minute or so.
This is the biggest measure of graphics success to me. Regardless of the graphics vs gameplay argument, I was a little disappointed at the beginning of the game (first 5 hours or so) that I didn't feel compelled to stop and look. I think seeing the Aurora was the first thing that got me excited. Since then, maybe because of graphics tweaks, I find myself stopping to look out over the mountains, taking time to run down to a river, etc. I don't care what anybody says, if a game makes you want to do that, the graphics are a win. And as much as I stand on the gameplay side, the candy and art design are much appreciated.