Hi Steve,
It's hard to judge the legs from the front but I can tell the arms are too rigid.
Here's a brief example of how overlap will loosen up a shape:
Arms_H.mov
The left arm is holding the same shape through the whole cycle, much like yours. That looks very stiff.
The middle arm is has a different shape for the front and back keys. This looks a little better.
The right arm was keyed in the same positions as the middle arm, but the rotation of its Upper arm lags behind the translation of the shoulder, and the Lower arm lags behind the Upper arm and the Hand lags behind the Lower arm. Every bone is a bit behind the bone it is attached to which is typical for a chain of bones like the arm. If there were fingers on this arm they might lag behind the hand.
I've exaggerated everything here but without overlap CG models look very stiff and weightless.
The mass and inertia of a bone (in real life) is what makes it resist any change of motion by the bone it is attached to. The animators challenge is to move the character as if that mass and inertia was at work even though a CG model has no mass or inertia.