This is one of my very favorite Sora/Xion pics of yours. X3
(Thank you, by the way, for posing Xion delicately enough to avoid a classless panty shot. XD I appreciate that!)
The overall effect is gorgeous, the dark colors and background paired with the beautiful drifting lights.
I like the looks of awe on their faces, like they're seeing something so breathtaking that it lifts their focus out and up, yet the fact that they're in each other's presence deepens the impact of the experience. They're not even looking at each other, yet they're still strongly connected through touch, the way he's holding her and she has her arm around his shoulders. I'm sure that this is a moment they'll treasure in their memories for a long time to come.
I also really like the visual theme of, "When I'm with you, I can touch the stars." X3