It probably doesn't seem so big anymore, but some of my first Xbox 360 games just made me think "Wow, that's some beautiful looking stuff." The first was when I first played Halo 3 single player. I had been at friends mooching playing his, but when in single player the graphics are so much more in your face and a lot less, oh look he just stuck you, ow.
Then when I got Oblivion I watched the intro and the whole view of the Imperial City was just amazing, especially since before then I was playing Morrowind, in which everything was very strictly polygons and the leveling made me throw my controller and hate pterodactyls.