One big issue, and a lot of people have this issue when animating walks or run cycles and thats forgetting to have a frame for the overlapping or crossing of the legs. Its one frame but it basically completes the animation.
Here's an example of that. Fire Running Redone
However I didnt do any clean up so consider adding in those extra frames on your own.
I love the design. However I just feel like the legs dont move. Maybe more contrasting colours?