One aspect that will be glossed over is Mandela's period as an underground revolutionary just prior to his capture and celebrated, if that's the right word, imprisonment. It was Mandela who convinced the ANC leadership to wage armed guerilla struggle. It was Mandela who worked closely with South African communists and co-founded the paramilitary 'Spear of the Nation' (MK) organisation. It was Mandela who sourced weaponry for MK, and led bombing campaigns - albeit with the express intention of minimising civilian casualties. And once at Robben Island, Mandela became the head of a cadre school for ANC and SACP revolutionaries, not many of whom passed on to legalistic, non-violent political action.
And yes, this revolutionary activity was entirely justified. At that particular time, in that particular place, when change couldn't be carried by peaceful social movements and the ballot box there was nothing else left. Politics will always find a way. As such, the ANC's resistance to the apartheid regime is a chapter of history written in the anguish of the tortured and the blood of the fallen. But it was this intense struggle that kept Mandela as its figurehead, and his own incarceration inspiration as its example.
The crisis of the apartheid regime was bought by the blood price the ANC paid. It was the revolutionary struggle that forced the government around the negotiating table. Then was the right time for the ANC's strategy to switch from armed confrontation and insurrection to winning political and cultural hegemony around a post-Apartheid project. The subsequent truth and reconciliation process, which saw some of apartheid's worst criminals escape justice, has proven its worth by consolidating the transfer to majority rule. Like any good revolutionary, Mandela knew 'by any means necessary' meant just that.
Like all revolutionaries, Mandela was a flawed human being forced by event and circumstance to fall short of of his ideals. But his work and the movement he led opened South Africa up to democracy and tolerance. It is not paradise, far from it. The 'rainbow nation' is beset by political tensions and economic problems - but the path of achieving permanent progressive social change is much smoother than it would be were it not for his efforts.