This has been very nicely excuted, and I like it, great composition, and also love the textures of the horse.
I would also like to see this in Black and White version as well, as I think it would be very dramatic.....
love how this fades into the background, and nice tones. i would put it a bit off-centre, would be more appealing to me. maybe to the right, so the horse is looking into the negative space.
Oh I love the deep black tones of not only the background, but the halter and the horse himself. Nice how he just blends into the background, yet the lighter tones keep him in the forefront.