It's a very well made piece, and the humanization is one of the best I've ever seen.
However, some minor details do tend to pop out at me. Mostly small things, like the detail in her hands, or the minute detail on her robe's arm.
This is more of a personal taste, but the shoulder and upper chest coloration seems off to me. I would have kept that skin tone, just to keep it more natural. It seems a little artificial to me as it stands.
Generally in the series, I don't believe I've ever actually seen the moon not full. And when it is, the Mare in the Moon is quite visible.
I'm a huge fan of symmetry, if that's a sash on her hip, again this is personal opinion, there should probably be an additional angle from the other side. Perhaps not another sash, but something to correspond with it.
Though the colors are quite good, and very vibrant, the color of the skirt and the sash fight with my eyes. The look like the colors would work, but something about the way the sash stands out bothers me. It seems as though she is a floating torso, perhaps.
I hope this helped a little, and if you have any other questions please feel free to write me.
Also, I've marked you down on originality, not because your peace isn't amazing, it really is well done. I've marked you down on that being that Luna is one of the most humanized characters in the entire series. Might I recommend Celestia, or Cadance. In fact, Shining Armor and Cadance (Cadence?) I don't believe I've ever seen.
How else could I describe this work of art? You've perfectly captured Luna's personality!
I love how aristocratic pony Luna looks and her human counterpart is no different. They both have an aura of authority and royalty around them both. Also Luna's expression demands respect, in a way. I'm not saying she looks snobby or anything. It's just that you made her look like a true princess to put it that way. I love her expression and I also love the dark colors you used. Her clothes... they add the finishing touches to her perfection. Great job!
May night take my soul, and guide my dreams, Teaching me that life is not as it seems, For too often the sun doth betray, Hiding behind clouds which covers is ray, But night is forever dark and deep, So bless me my Princess, with blissful sleep.
Ninja-8004 If I didn't love Luna before...I DEFINITELY DO NOW!!!! WHY...wasn't THIS and YOUR Celestia the model for them in Equestria Girls?!?!? The movie sucked (no offence to those who liked it) but if the characters looked the way YOU drew each of them (including the Mane 6), it would have made up for it!!!!!