Would you like a critique? I'd be happy to give you one but I'd hate to overstep.
Cutting - Good, a bit bumpy in some places and a bit hazy in others but overall nothing to complain about
Mane/Tail smudging - You need more indevidual strands in there
Light/Shadows - This is the biggest thing. If you look where the light is coming from (The moon) You can trace where the lights/shadows on the horse should be. The side of the horse we see should be in shadow, unless there's another light sorce we can't see. Without shadows it seems to look like the horse is glowing
I know you didn't have an inspiration for your manip, so I won't comment on that
Overall I think it's very pretty. Not many people can pull off a black and white manip. Well Done :)