Because I know you're amazing at this, I'm going to go ahead and offer one little critique, and hope it is helpful...
There is a problem, in my view, with Tony's beard and the big rivet-thing on the suit behind him. They are so close to the same value that they are joining together visually and becoming a little confusing, as in "What is that sticking out of Tony's chin? Oh - now I get it." Yes, it's a problem in the lineart as well, but I think you could fix it by making the background there just a hair darker, thus moving it back in space and differentiating the planes a bit more.
Take this or leave it!
May your awesomeness never fade! I really do love your work, man.