Really great work, this piece captures something about fluttershy's innocence, and it also captured my eye above the thousands of other artworks that come through deviant art every single day.
A slightly critique on some of the proportions, in particular her nose, ear and thighs. I think maybe her legs are a little too far apart from one another to make it look natural. There's something about the way her legs cut off at the clouds that I'm not sure I like but to be honest I can't put my finger on what the issue with it is, perhaps not such a hard cut but more of a fade would have worked better?
The way the clothing fits and falls around her upper-chest is very well done. As is the flow of her hair and the shading of the whole piece. Excellent job and I look forward to seeing more of your work!