On one of the news shows(probably CNN), they made a point of how when Mandela was elected president that he intentionally avoided any retribution and kept the government officials in their jobs. These were the same people that kept Apartheit going. Many in South Africa were calling for him to at least fire these people--or worse.
Even though it took longer to get rid of Apartheit, it was a much more peaceful and stable transition of the government--unlike what's been happening in Egypt and other Middle-Eastern countries the last few years.
Just an example of what Nelson accomplished where others have failed.