I think the legs swap a bit of color on the run, and it looked like there's a bit of a lurch that could be fixed with a bit of blur or an extra frame.
I could use a bit more arm movement/shape and maybe a bit less head bob.
The jump/fall is missing the actual jump. There should be at least a frame of the character squishing down in order to get power. The front arm also loses a pixel.
The attack could go for a bit more follow up between swings. A good way to do this would be to add in another extra frame immediately after he finishes the swing, with a bit of blur still on it.
I'm kind of nitpicking, but they look really good. It's pretty clear what's what, which is really important for this size/level of detail.