it is not looking bad, but the neck seems a bit long and his hoof should be solid and stiff, not as...well, bendy and his back leg seems a bit smaller. try making the legs seems like one motion. it may just be me. however, you are the artist...the final critique should be you to decide. also, is there another piece where he has his head? it may be more helpful to give a better critique.
and please note that this is my first and only critique i have ever done. and i said earlier...you are the artist. what happens is up to you and only you.
I studied what I was going on with the neck and tried to make it less stiff, but that made the head bobble like crazy. I noticed that the back hooves were going down further than they should have and made corrections. The neck was long since most of it is covered by the head and it gives me freedom to give the impression that the neck elongates or shortens depending on what's going on in the scene.