I was a captain on the NG and classic for many years and from a pilot's point of view I cannot say that there was any obvious difference in the autothrottle operation. I can remember only a handful of flights with the auto throttle u/s, so manual thrust lever operation in all phases of flight was a pretty rare occurrence and required some thought. Once you got your eye in so to speak it was simple. But it is not a mode everybody spends a lot of time practising on the line. Obviously you train a lot of the time in the sim without the auto throttle, but then again that is mainly one engine out and the aircraft does things more sedately. But it is frankly not the sort of failure that you would expect to cause anyone a lot of problems.