Had a chance to take a close look at the frames, here the suggestions i got, hoping it'll help a bit.=)
fr1. Seems okay as it is, except arm length
fr2. far leg moved forward witch is rarely happened while body doesn't get full support with another leg - his front leg just step on the ground and do not support body just yet.
fr3. Heads position unbalancing figure a bit , i'd move it one pixel to the right.
fr4. figure falling backward - head again making sudden jump to the left. Also far feet might change angel, delay it's position a bit to make a floppy move as a joint expression.
fr5. falling backward again, normally it tends to fall forward with a leg up high.
fr6. falling backward once again - front foot is moving forward at the same moment another one just touch the ground.
fr7. Same as fr3.
fr8. Front leg shrink a little.
Hope all that make any sense to you.=)
Here a quick edit with some fixes, if you won't mind.=) Some changes i made not critical - just automatically, perhaps are the matter of taste.
