The thing is: I can't tell you any more about it. The less you know about it the better. But I just went to see it this evening—we were literally the only two people in the theater—and I'm still trying to figure out what I can tell you about it that will get you there but not lessen the power of the narrative.
To start: you should see it specifically in the theater because it's beautiful to look at. The environmental cinematography is stunning, and the archival photos look like something Bob Reuter might have shot in St. Louis; that is to say, gritty and enigmatic and iconic black and white images of fascinating characters in a busted-up city. And there are shots of South Africa that'll make you want to go there, pretty much guaranteed: a vista of city grid butting up against cloud-capped mountains, red rocky cliffs above a blinding blue sea, endless acres of African forest, street-level city life.
Also: "Searching for Sugar Man" is a documentary about a songwriter—you haven't heard of him, and you haven't heard his music—and his music is haunting, urban, pissed off, effortlessly classic. The music alone is worth the price of admission.
But also: go to the theater because you probably won't see it otherwise. Sure, it might end up on Netflix or whatever, but it somehow won't get seen. And then you'll have missed a true gem.
So don't read any more about the movie, don't put it off, and do get yourself over to Plaza Frontenac. Trust me on this one. And if you go, after you've seen it, write me a letter so we can talk about it, cos I can't talk about it with anyone yet and it's driving me nuts!