You're off to a good start. I'm more familiar with animation, so I'll leave the rendering critiques to the other guys. If this is your first animation, I'm impressed. I have a few suggestions, however. In the arm movement, take a close look at the hands in particular. See how his hand jerks around when it gets to his hip? It looks like he's shaking some dice or a can of soda. The motion should make a smoother curve (possibly in an elongated and bent figure 8 motion). Also, it jumps too quickly to and from the upward position. Unless it's supposed to be thrown up and down with extreme force, it should ease in and out of movement. Animate different arm movements for the up and down motion. Don't use the same one both ways.
As far as the legs go, you've communicated the point of contact, which is good, but it looks like his hips/shoulders don't swivel at all. They should swivel slightly in opposite directions as he walks. Maybe a lot if you want to exaggerate. But not swiveling at all makes the walk look robotic. I also suggest a bit of clothing movement. Perhaps a slight hat tilt on the way down, or slight movement in the piece of cloth sticking out from his chest (scarf? unless you didn't mean to do that). Hope this was at all helpful!