I own a swing coat that looks just like that (well, other than being made for a human. So...essentially like that?). Actually, it's my only coat - but I don't need any other. I love my herringbone swing coat!
Nice characterization. The clothe fits nicely, halfway between what a non-sentient horse would wear and what a character from MLP would use. Also, it is nice to see some art from you that reminds me of the Conversion Bureau.