I just used it on the 707 demo flight.  I turned it on on the overhead, switched the dial on the console to auto and loaded my flight plan.  That gave me distance, but I had to dial in the course myself (glad I had something to do).  It followed the flight plan perfectly, with the distance rolling down as we went.  Beyond that, I don't know.  .  I did try a multi-legged trip before and it followed the legs nicely, but all on the A side.  I am thinking there is supposed to be some switching, but I haven't experimented enough yet.