This is absolutely beautiful. You have perfected Luna into a Goddess, not a mere Princess.
He style, pose, vector, mane, pallette, accessories, , wings, are brilliant.
The mane is sparkly and smooth, perfect size. The Accessories are Royal, Important, and perfectly synched to her glorious, curved body. The colors are vivid, but mysterious, and her expression is of Majestic Mercy, and Understanding. The wings are expressing importance amoung this Queen, and they take control over the artwork, making them one of the key parts to this vector.
I have never seen more precious and realistic vectoring approach to Luna's greatness than this one. Little details just add so much variety, and still the simplicity in the piece Reigns among all other aspects of it.
In conclusion, it's Wonderful. I have no other words to say about it.
Thank you very much!
Some parts were changed at the last minute - e.g. the raised leg, direction of her eyes and addition of some larger sparkles. I'm glad that the changes seem to have paid off.
In fairness, I should probably mention that the crown, necklace and wings are all the same as Celestia's, with edits and recolours as appropriate.