Great comment. It's hard to explain it fully without feeling it for yourself (my impressions will be out later on today), but it does 'feel' completely different. For long-playing Tiger fans there is definitely going to be a learning curve on higher difficulties and there are over 60 million different shot variations and possibilities in the game. Your acceleration is based on the speed you move at and trust me - on higher difficulties this game is no longer an easy play.
Every shot out of the bunker requires thought and care, same with deep rough. No more hitting shots 240yds. out of the rough. There is also a new ball marker for spin control which requires you to hold down the right stick at the position you want to hit the ball WHILE you swing. Shot making is a thoughtful process now but on easier difficulties this can all still be toned with options.