Robert Paul Wolff, as I had hoped, provides some useful commentary. Let us not forget that, during his long career, Mandela was an advocate of what would now be called "terrorism" against the South African state, and correctly so. He survived a quarter-century of unjust imprisonment, and yet, remarkably, assumed the mantle of political power without seeking revenge. He was a very unusual man, whom I suspect we do not yet understand, but Professor Wolff is surely right that there was something "great" about him, notwithstanding the debasement of that adjective by its promiscuous application to war criminals, political hacks, and servants of the ruling classes.
UPDATE: Ruchira Paul points out to me that Mandela was only removed from the U.S. "terrorist watch" list in 2008!
ANOTHER: Right-wing crazies never disappoint!
AND ANOTHER: Albie Sachs, a former justice of the South African Constitutional Court and himself a most impressive and remarkable individual, made an illuminating and moving set of remarks about Nelson Mandela several months ago.