Those wings are just amazing, as is that mane and that tail. And the way the neck bends... impressive. The lighting from the star is handled really well, too. Overall, it's a very, very impressive piece. Great job!
I like this piece a lot ... i would recommend cropping off the empty space to the left though, it somewhat throws off the balance of the picture ... or perhaps have the moon (or something) peeking in over the left edge
the actual art of the piece you have is wonderful ... the arora borealis type lighting from the star is done beautifully and i love how the lighting on Luna's body changes to match it ... I also like how the feathers on her wings are of two different colors. not a lot of artists do that and i think it makes her seem a little more real