This is my favorite of your mane six at the Gala. I'm pretty particular about how snouts are done (not sure why), and you stay more true to the show's style while giving it more realistic coloration/shading. I think of the mane six, you did her snout the best. You didn't use hard lines to define it, and even facing mostly forward, the shading gives it nice depth and avoids being too flat. Really great.
Overall this is a great pic, and I don't want to seem overly critical, but there's something not quite right about the face. My gut tells me it's something about the eyes, but as I look at it more closely I think maybe it's because the snout isn't defined enough, sort of giving it the appearance of an alien face rather than a pony face.