We were advised to ensure that the aircraft was slightly out of trim before connecting the AP, so that it had something to 'work against' - otherwise we were told that it would tend to hunt. I never did find out whether this was true, or just BS.
On an Auto-ILS, the aircraft was quite lively. There was a 180KIAS limit for flying with 'Track, LOC+GP' selected with the AP.
Flew all the way back across the pond once without an AP - we took 20 minute turns to fly the jet.