I like what you're doing with his skin's texture--is it supposed to mimic scales? It could use some work though, especially the bright spots around his nostrils; they don't blend with the other spots to me.
The shading on the bottom on the hat gives it a tilted perspective--is it supposed to not fit over his all the way? Is it tipped to one side? If it's supposed to be straight on his head, take a look at Souly's edit and see how the hat sits on the Yoshi's head.