There is one more noticable difference, The quartz movement actually keeps time. The only time I have to set the time in mine is if I disconnect the battery, other wise it can sit for weeks at at time and still be right on. The old wind up movements would be a half hour off by then.
If you are good with your hands and can read and follow directions it is not hard to do the swap to quartz yourself. Takes more time to get the clock out of the dashboard than to do the switch. Turn around time..... one afternoon.