the roll looks good, but theres now up/down movement on the run cycle so it looks a bit weightless... the head goes up and down every two steps (should probably be every step) and there should be some more obvious weight transference... if he's pumping a sprint there should be more 'jumping' and 'landing' with the whole body pushing against the ground.
As always, i can't reccomend Richard Williams 'Animator's survival kit' enough!
Yes that's meant to be a good book - i just can't believe amazon.com is $23 and .co.uk is £23! you'd think they spent too much time with Adobe - its twice the price?!
Anyway I guess i'll wait till I'm in NY in September and get it there!