These aren't bad.
However, in the walking animation, you should try to give him some "bounce". At the high point of his step, he should probably be at least 3 pixels higher than at the recoil stage of his step. Make his leg extend as he goes forward, and crunch as his foot hits the ground.
You might also want to make him lean forward a little bit, as this lends towards a more believable stride. Each step one takes, one is essentially allowing themselves to fall forward, only to catch themselves with their feet.
I think the arm movement is a little weird, but there's nothing technically wrong with it, and it's hard to critique without knowing what kind of personality you're trying to convey.
The punch looks a little weak, you might try twisting his torso a bit as he punches, otherwise it looks like a little rabbit punch.
The kick isn't bad honestly, though more frames might do it better justice. You should also change the timings on the frames. The frames as he is striking should be fairly quick, maybe a 70ms delay at most, and the ones where he retracts his foot back to the ground can probably keep their current speed. The idea is the actual strike is fast, otherwise it conveys no power. Post strike, speed is of less importance, and can afford to be slow to conserve energy.
These are pretty good rough drafts, and I can see them being great with the appropriate tweaking and finishing touches.
