And I also have to disagree about Vito being a good don either. He was when he was young - no argument there. But his refusal to modernize the business (i.e drugs) was a fatal error. He alienated himself from the rest of the dons and underestimated the consequences of his old-fashion behaviour. Add to that the fact that he chose not to avenge his son, and you may praise his dedication to peace all you want, but at the end of the day what the other dons saw was a weaker don, like Michael told him "a sign of weakness".
With Vito it was a case of Morals vs the times.I like the fact Vito had morals and didn't want to get mixed up in putting drugs out on the streets personally.