My first wallpaper of, Princess Luna.

So I thought that it was good overall. Some minor things could be pointed out though. One thing is that the bottom would be too dark and if you look closely at luna she looks like a transparent pony like in For Whom The Sweetie Bell Toils. You know what I mean. I do think the rest is perfectly fine and it would look perfect for a wall. Oh, and the transparent part of Luna's main should match evenly when it is just a still unmoving image. I ideally think that you should consume more time on the contrasting so it could be more refined.