I love the way you've done the lighting in this picture as all the shadows fall perfectly. The folds in the clothes are great for each character creating a greater feel of moment in without being overdone. The slight differentiation in shades of the clothes on each character stop the outfit from just blending together and the hair styles also clearly show each character without having the shows mane simplicity.
I found the cutie marks on their legs to be a great stylistic inclusion and just as derpy's wing with the design of them fitting your style perfectly.
Just like all the other human-pony commissions here: I love it!
But i'll find you, and i'll hug the hell outta you