His steps are syncopated; he does not make even strides. You have an accurate sense of the way human bodies bend (I like the his swing of his arms) but the timing is off. If you pay close attention you will see that he's taking stutter-steps instead of walking continuously.
...urhm, good job animating, but if i see a naked man walking towards me with that face on him...i am running...actually, i am running if i see a walking naked man period...
looks good, I think you should focus on the torso (abdominal muscles) ...those should be moving a lot more than thyey currently are. This is a really awesome and fairly accurate representation of how a human being walks, much like epoxy said before. with minor adjustments, it can look even more life like. good work