It's quite a beautiful picture, but I feel like they're a little too slender right in the middle point. It doesn't look like they could even support the top halves of their bodies with how little their waist is. I understand as ponies they're slender and graceful, but to this degree, it looks a little unnatural. Other than that, a gorgeous picture!
I love the design of Celestia's face, and the way you did her mane/hair. Gorgeous. However, I feel that Chrysalis is a tad....too pretty. Personally, I would've loved to have seen her with a more gaunt look, and a paler complexion. She may be a pony when not human, but she's an odd looking one. I just wish that'd translated better. Love her hair though!
I undersand the point, but the 2 princess dont share any color, and is so notable that one is white and the other is black. In my case I think this color skin look very good in Luna, i don´t wanna do it white.