This movie was put together with some arresting visuals used under audio clips from Frank's shows-- not that this is the best way to enjoy Frank's art, but what other choices did the director have if he wanted to include portions of his subject's work in his film? (The best way to take in Frank is in a room alone with the lights out.)
For a decades-long fan like me, it was enjoyable to hear and see Frank's collaborators and friends talk about what it was like to know and work with him. But it wasn't really what you'd call a deep dive into Joe Frank's life or psyche, and I didn't learn much that I hadn't already read or heard from Frank himself through his show over the years, apart from the circumstances that led to his leaving KCRW. That revelation was a bit of a shock. Oh, and the interview done with one of JF's collaborators did buttress my hypothesis about his death in 2012.
If you're not a fan, would this be worth seeing? Hmm, not sure. It's hard for me to be objective about that. But I suspect a better way to familiarize yourself with him is to first listen to one of his shows. If you like it, listen to another (his old shows are in rotation at various radio stations around the country, and are also available for purchase at his website). Then, if you become obsessed with him, or simply curious about how someone could come up with these ideas, watch the movie.
Or maybe it would work just as well in reverse.
(Addendum to review, July, 2022: While reading court documents pertaining to a suit brought by Joe's widow against the filmmaker, I learned that she and Joe had a financial stake in this movie-- a fact not publicly disclosed by any of the parties until the lawsuit. This arrangement, clearly, should put the movie in a different light for anyone considering watching it. It should also, perhaps, put it in a different category than "documentary" altogether.)