Well, here's a suggestion: Make it so the arms and legs go in the direction you push relative to the screen, not the gymnast. So if I press left, the arms will always point to the left side of the screen. Also, it would be nice if the arms weren't restricted to 180 degress of freedom, as well as the legs being able to be moved behind the body.
I know you're going for realism, but sometimes realism isn't that fun when it makes it almost impossible to grab one of the nodes.
Oh, and the arms should have elbow joints, too. So the amount the arm goes out depends on the amount I press in a direction.
Finally, there ought to be a way to regulate how hard the guy's gripping on the bar. Maybe if you press in the left trigger all the way he's gripping tightly and his body won't move relative to the point he's holding. And the more you let off the trigger the looser he holds on until you just let go of the trigger and he lets go.
Otherwise, awesome game!