Personally, I really liked Doc as a person and thought he was a good, not great coach. The decision to leave turned out to be a good one for both teams. His teams have been in the playoffs the past few years. Yet, competed in a much tougher division than us. So, can't fault him for lack of success there. He's also had the worst luck when it comes to injuries....Chris Paul and Blake Griffin come to mind.
One added bonus is he got to have his son play for him. That, in itself, would be like winning 5 NBA Championships for any father. Can't get better than that in the basketball world.
My main complaint about him in Boston was his inflexibility when it came to player rotation. The starters would finish the game no matter how well any member of the second unit was playing.