The blocking pose looks rather odd. What's he doing?
Oh, shoulda specified. That's a gethit.
The back is arching, so I think the neck and head should go further down, and the darker arm should go further back and its fist not get as big?
This area of his hair looks strange, considering the angle. I get he has long, unruly hair, but from this view, it shouldn't stick out this much unless the wind was blowing in that direction or he jumped back or something.
The attack animation is pretty smooth, but the shading seems to jump all over the place in that one. like how the torso suddenly becomes completely dark when it had plenty of light on the first frame. It's mostly prevalent on the arm and the torso.
There's some of that, too, in the hit pose, as well as the hair issue I pointed earlier. Except this time, he seems to face completely sideways, yet his hair remains at the same angle. His hat also seems to shrink for some reason?
I like the design though, so I would like to see more
vary your frame speeds, friend.
also, i'd recommend adding another frame for motion blur. right now, your right arm is going such a distance between frames to get to the punch that it looks like the left arm is punching instead because of its close proximity. if you don't want to have five frames in your animation, consider changing the first frame of the actual hook into a motion blur frame. the viewer really needs to see where that arm is coming from!