Try to cut out those repeat frames between the end of the one cycle and the beginning of the next. There should only be one frame of the "neutral" state, other wise it looks like the character is stopping every time they take two steps, then taking two more steps, then stopping, and so forth.
Otherwise, it looks pretty cool, I like the style, and unlike everyone else's comments I think the big feet is unique and makes the character feel more personalized :)
Last recommendation I have would be to put some more effort into the backgrounds to make them more interesting! But I get that this is mostly a test, so it's forgivable.