So far it looks amazingly good. It's a great three-dimensional style, so it captures Fluttershy's happy side from all angles. Along with the great face, I very much like the style you chose for her mane. There's a lot to be said about the composition, but I'm sure there are lots of things you thought out.
The bird is a terrific adornment, especially to give a better "explanation" of why she's feeling so good at that very moment.
My main two goals for this project were to make an interesting composition and to capture Fluttershy's personality. I had thought about doing one of the other ponies, but I couldn't think of a a way to properly capture their essence. This idea was just too perfect not to follow through.