I think the animation doesn't make any sense - it really doesn't seem he is running. :x
You should slow it down and re-check the hand and the feet movements. :x
Maybe this link could help you in this! :)
http://www.freefever.com/animatedgifs/sports/running.html
Try to fix your animation and it will be great! :)
I Think the animation is supposed to look like that. its a cartoony kind of effect. But it could really use some work. the 2 shades for the feet are so alike that I cant see that lighter shade without leaning over my computer screen. Also, the wavy arm effect and the slow moving 'Hands' dont mix. not being offensive, just offering constructive criticism.