Just starting to scratch the surface with 3DS Max, looking at rigging and animation with CAT (Character Animation Toolkit). The navigation takes getting used to; accustomed to Maya's interface. I love how Max crashes whenever you press a wrong button; it is like touching a hot stove. Eventually you learn not to press whatever incorrect button.
So I have the medic character from Team Fortress and using CAT, went about making a rig for him. On a more serious note, the system will mirror over multiple arms/legs/etc that is made as long as you have your rig sitting on the axis, which was nice.
