This is a really great sig. The lighting is dope although I may say it extended a little to far out to the edge/was still too bright as you neared the edge of the sig. The flow of the sig follows the render correctly. The black and white composition of the entire signature works really well however there are some brownish orange floating things that are somewhat off putting. Certain parts of the sig are over sharpened like directly under the arm on the chest, then again on some of the arrows off to the right of the signature. I would have also liked to see some more effects on the foreground of the signature(in front of the render). Otherwise like I said I think it looks great and can't wait to see more.
I agree with xVitalz, the brightness is a little to much toward to top and right. You did a great job with the flow, even though arrows are cheating . The over sharpness under the arm the xVitalz mentioned is a bit distracting, appears to just be part of your clipping mask layer bleeding through? The brown/tan specs do seem a bit out of place, you could have incorporated them more by saturating the render a bit so you had a slight tone for everything to blend.
As far as composition goes I don't care for the size of the signature. Realistically I don't see anyone putting an image that large into a signature, but maybe that's just me.