I agree with what many have said. Micheal was a really good Don but he had lost the ability to open his heart and was far too controling. much of this has to do with the diffrence in the times. "things change" just like he tells his mother. Women no longer simply bowed down to their husbands, brotheers didn't always love and respect their brothers, and mafia loyalty was quickly eroding. He also had to create distance between himself and others in order to survive.I believe that mike earned a reputation for being cold in part due to the way he begins his term as don. With the aid of Vito he eliminates the other heads of the 5 Families as well as others like Moe Green. This earns him respect through fear. True he didn't have the heart of Vito but he was just as smart and much more ruthless. Micheal also had a good head for business and made the Family rich and respected. It would have been hard to fill the shoes of a great like Vito (as he states in II w/ Fredo) but Mike was easily one of the great Dons of his time.