a super soft blur brush along the body edge might help with the realism (its a very sharp edge with no feather).. but as always.. just IMHO.. art is art good luck

The bottom underneath the creature looks odd, because while you have a decent shadow beneath him, there is nothing but the background sunburst showing - what is that shadow being cast onto?
You might consider making the area under him more "solid looking, perhaps by just darkening it, so that the sunburst still shows, but is not so bright. Especially since the top of the sunburst is darkened...