When you look at GDP//capita another story appears. During Mandelas Presidency, 1994-1999 GDP/capita stagnated between USD 3,546 and USD 3,102. However since 2002 GDP has risen from USD 2,439 to USD 7,942 in 2011. I am no economist to say whether this GDP/capita 200% rise over 9 years was due to inflation or because of economic policies put into place during Mandela Presidency.
If we take Sri Lankas history Parakramabahu the Great was a great leader who united the country oversaw the expansion and beautification of his capital, constructed extensive irrigation systems, reorganized the country's army, reformed Buddhist practices, encouraged the arts and undertook military campaigns in southern India and in Myanmar. The adage "not even a little water that comes from the rain must flow into the ocean without being made useful to man" is one of his most famous utterances.
However such success came at a price. Relentless warfare took its toll on the country and Parākramabāhu's reliance on Tamil mercenaries proved to be a destabilizing force after his death. Taxation was high under his reign and high-value coinage all but disappeared towards the end of his rule, a sign of increasing poverty. One of his successor Nissanka Malla's (a non Sri Lankan from Kalinga) most popular actions was reducing taxation.
The chronic instability of the years after his reign undid many of his accomplishments and developed into a crisis that the country never recovered from.
His ultimate weakness was the lack of restraint in his spending, taking Sri Lanka to greater heights that it had reached in a long time, but exhausting the island's resources in the process.To me the take home message is that however great a countries leadership can be, the leadership can only solve some of the problems facing a country.
Read this for a negative view of Mandelas legacy