Experts say not to worry too much about form. One of the great runners of all time, Emil Zatopek, looked much worse running that you ever will. He thrashed his arms and bobbed his head, and won four Olympic gold medals, looking more like Jerry Lewis than Carl Lewis.
Your form is greatly dictated by your biomechanics, by how your feet hit the ground. If you swing one arm widly, it may be for naturayl reasons to balance what your legs are doing.
That being taken into consideration, with all things being peftect, here are ideas about "good" running form.