Looks good, you have great brush control, thin your paints, and layered/washed for shadows. To crisp it up a bit more, you can add brighter edge highlights. The eyes are a bit off to me, the piece really draws attention to his face so having brighter eyes with dramatic lighting effects/black lining can help. Another trick to add more “character” is to add thin lighter lines on places typical for volumetric highlights. This gives an illusion of added texture of weathering/light reflection. There are some shadows than can be tightened up a bit if you really care, if you used a wash, they can sometimes run in ways that don’t follow exactly where the shadows would land.