What are some of the positive and negative things Nelson Mandela has done?

I have this friend who I'll call "Smith." Smith absolutely HATES Nelson Mandela, and once went on this big rant against him saying (verbatim), "He's basically a Hitler who everyone likes and who tries to act nice." Prior to this I had never given much thought to Nelson Mandela but he seems like a pretty universally respected guy, so I asked Smith to allocute his statement. Smith claims that Nelson Mandela supported terrorists and Communist dictatorships and ran his country's economy into the ground, yet is still popular because he "kind-of-sort-of thought about trying to make a half-ed effort to end apartheid." Exactly what was the extent of Mandela's involvement in the fall of the South African apartheid rule, and is there any truth to Smith's claims about him being a nice Hitler? Please cite credible sources because I don't want just a bunch of conspiracy theories.