This man has a good recounting of Mandela's interaction with Communists. I trust his opinion, mostly because of his personal knowledge of South Africa and his ability to connect that knowledge to his studies of history.
It's an open question whether Mandela's jail time (and his involvement in terrorist-style attacks) are absolved by his later deeds. I can't say much on that. I hope that Mandela's death does not portend a change for the worse in South Africa.
Another comment which I found enlightening is in this comment-thread on Mandela's death.
The South African struggle against apartheid was seen in this country through the lens of our own Civil Rights struggle.
It was much different. ... it was also the rise from utter disaster of the Xhosa people, of which Nelson Mandela was one.
South Africa didn't have two imperial powers --- the British & the Dutch --- it had three --- the Zulu. The Zulu Empire at its 19th century height had an estimated 14 million subjects. All three imperial powers shared one thing in common: the Xhosa were to be a subject people. Under apartheid, the Zulus had, then as now, much self-determination in KwaZulu, and they often backed the apartheid regime.
The rise of the Xhosa under the ANC was not just a white vs black or an anti-imperialist struggle. It was the story of a broken & despised tribal people rising to power from the ashes. It's a story that is much more interesting in its own terms than in the terms that the rest of the world uses to it.
It appears few outsiders understand the differences between various tribes present in that part of Africa.
And it is easy to forget the racial and tribal animosity, as well as imperial aggression, can be found between those African tribes.