The image is beautiful, no doubt about it. I still have quite a few things to say though...
1) I believe the blur is too much. For next time try making 2 layers of the background, putting your regular blur on the top one and then reducing the opacity.
2) Maybe add a bit more detail to the mane? The highlights aren't completely visible.
3) looks too good. Let me borrow a part of your skills! You are simply amazing!
Thanks for using this photo! I would've hanged this image on his stall door if he would have been alive... I miss this stallion so badly. He was a sweetheart!