In conventional aircraft when you make flight path change or thrust change visually the tactile feed back and speed stable behaviour provides additional cue. Airbus FBW in manual flight you fly only by visual cues. The changes to flight path, speed and thrust are visually noticed and effected. Not only there is no feed back in the stick, the flight path stable aircraft does not pitch up or down to speed changes, power changes only large increases will cause a dampened response. In airbus since any displacement of side stick is a demand for change either in pitch or bank the stick needs to be in neutral most of the time, it is essentially intermittent contact flying. Basically in manual thrust in any aircraft pitch changes require thrust change but in airbus you only see and do as your hand will feel nothing. It is different but not difficult. Elevator integrator holds the elevator where ever you leave it and trim catches up automatically. The aircraft is always in trim. But pilot always needs a good scan. It is immaterial whether AP is on you still scan instruments in the same manner but only watch changes happening instead of making. In SFO they never monitored the speed because may be over confidence in automation or it is possible never developed raw data skills in the first place. Design of the automation had nothing to do with it. Any one who has the skill can maintain it with very little practice.