Much better than the ussual fan art crap.
This is a lot of detail and so much better than the usual crop of fan art than ends up in the art portal.
It's actually a really complex drawing with that attempts to be an imitation of real life than other peoples drawings such popular examples would be anime or other cartoons.
I don't think it is too much to ask to create an original drawing and when you do fan art than try to add your own twist to it rather than arbitrarily coping it down to the last detail with understanding why.
As for improvements i think the lights and shadows on your drawing is all over the place and i have no clue where the actual lighting source is.
But other than that it's awesome and keep them coming.