Overall, this looks really good. I could only round up a couple of things that I think could be improved.
1. I think there could be a bit more detail to the rivets on the belt.
2. The gaps between the gaps in the mask seem to not be dark enough. It looks like they should have the gaps between each of the rivets, but I don't see them.
Now for what I like:
1. The skull on his belt looks dead on, great job.
2. I like how you made the fabric for the vest. It is almost an exact match for the reference image.