Princess luna {Final edition}

This is a very good drawing, and I'm very much impressed.

The eyes are beautiful, but they don't stand out enough. They actually look kind of hazy. I suggest you make the lashes darker or thicker or something to make them more noticeable.
The mane and tail are beautiful, I love the blue-ish see-through outline. Overall just the right amount of translucency. I'm having a hard time deciding if I like the purple at the ends of her hair, but it does look good and interesting.
Her cutie mark done very well, nice and accurate. I love the glowing effects of all of the moons on her, especially on the cutie mark.
Just a note- the crest is usually black. I have nooo idea if making it silver instead was intentional or not, and it looks good like it is. I just thought I'd point that out. I like the extra spots and jewel on it, and the moons on her shoe-things. They're a nice touch for the character.
If her muzzle were more squarish, she'd look more princess-like, but that's just a minor suggestion. It looks fine like it is. I would suggest making her wings a little longer, especially if you take my advice on the muzzle thing. I feel like it would go better with either both or neither in your style, though I'm not entirely sure how to explain how. Also, just a personal opinion, I think it's really cool that you gave her wings more like Nightmare Moon's.
The color and shading are beautiful, and if you added a dark background to this, it would look even better.
One last thing I want to add in here before I wrap up is about her body shape. I don't know exactly why, but I love it sooo much. It looks great and fits the character without being so dramatically thin like in the show.