This looks really cool. I like the way the hair moves after he does a strong punch.
I guess I only have a few nitpicks, maybe they will help:
1. During the quick punch, the shading gets less thick on his jacket and crotch. For example, while just standing, light is not hitting the "fly" of his jeans, but when he starts punching then it becomes lit. His hips don't really turn so I don't think they should become lit as if they were turning into a light source. On the jacket, notice how the shading is quite thick on the bottom, but then when he punches the shading becomes very thin, like the jackets folds are becoming sharper. If anything, when he punched, the pull on his jacket would reduce wrinkles. The shading also nearly goes away on his right arm when he jabs.
2. It looks like he is blinking while throwing the quick jab. That is not when I would blink.
3. I would speed up frames 12 and 13 to maybe 5ms. I think it gives the punch more power, but maybe that's just me.
Good luck.