It lacks a lot skin detail and shading where it should be in some places, give it some more texture and give it some rough feel, you can worry about more shading later.
Add more tiny scales, because the dragon looks like it's a jigsaw puzzle.
Also it looks like an older dragon so add some more detail on it's teeth, because dragons have eaten something sometime in their life. But keep in mind this is just an opinion you don't have to do anything of the sort.
All in all its 8/10 work to me. :)