A lot actually.
Story, I love the story lines.
Music, thought WoW had some great music, but some pieces in this game blew me away. They still do, no matter how many times I hear them.
MSQ, big part of my enjoyment. I love questing.
Contrast in some things. Writing on parchment with quill and ink, while having an advanced spaceship. I love that. Always makes me smile.