He is a handsome boy, and there are a number of Barnvelder colors, one being Dark Brown which he may be exhibiting. He is not the expected Double Laced male coloring.
It's hard to see his conformation from this back angle. Can you get a side shot as well? What color is his chest? His legs look more white than the standard yellow, which is a flaw.
I think he may be a Dark Brown Barnevelder. Are you planning to show? Breed for sale? Or simply for hobby interest? I breed for egg color, so I forgive some color imperfections, but am always careful to sell my Barnevelders as "utility" quality. I get lovely terra cotta egg shell genes from my boy. You may wish to pair your boy over some nice hens and see what happens.