My only suggestions for modification: Perhaps crop off a part of the left side of the image; that long line of the horse's back keeps drawing my eye away from centre.
I like the overall faded tones, but there is no central point of interest (either in terms of colour or focus). Try squinting - I just get the horses head as the stand-out point because it is large and dark. So perhaps the model's face needs a bit more colour/skin tone, or sharpness, maybe some blue in the eyes.
But once again - fabulous idea. Bravo. (and please re-post if you make any mods - would love to follow it)