I like the way you've got things wafting as if they're underwater. That's just great. The squash and stretch on the shorts is really cool, the hair movement is a delight.
My nit-picks are thus:
- Light source! Where is it? I'm confused by the way the highlighted and shaded areas behave. To the right and above? To the right and below? Why does it move from the top to the bottom of the swimming arm? Why isn't the face lit? Or the gun?
- Light and shade. You're using just one line of pixels for this, which I sometimes think is a bit of a waste when you could use it over more area and get some volume and definition into the piece.
- The shorts are a single colour and outlined all the way around, but the arms have highlights and the legs have shade. I find it a little inconsistent, as if the different parts come from different universes.
- The way the legs move, it seems to take the same amount of time to pull the legs in as it does to release them back to a straight position. When swimming this kind of stroke, the wind-up is usually longer and the straightening action is short and explosive.
But like I said, nit-picks.