you did an amazing job but...
The head... for some reason it looks rather small compaired to jis horns on the back of his head and his neck... It just doesn't seen to look right... Maybe try extending his head a litle more or slightly narrowing his neck or something.
one other thing, is he supost to be a painting on the wall? if not, he looks like he is, you need to add in some shading on the wall, like around his head, it looks flat abound that part.
Great drawing nonthe less. you just need to do a few touch ups here and there and it'll be parfect :)