Alejandro Jodorowsky became infamous in the early 1970s for his incredibly weird and violent surrealist movies "El Topo" and "The Holy Mountain." After that, he got the rights to Frank Herbert's Dune. This movie details the extensive work he and the crew he assembled did on the movie. I knew before I even saw this movie that I would have hated Jodorowsky's "Dune" had it actually made it to theatres (because of the extensive and incredibly bizarre changes he made to my favourite work of science fiction), but it was fascinating to hear how he went about it. The man drew some of the world's best talent around him with remarkable ease. Where it all stalled out was that Hollywood studios weren't interested in making the 6-to-20-hour weird vision that he'd created because of the cost and the fact that it wouldn't sell. The latter point didn't particularly concern him: the artistic vision must be followed. Jodorowsky saying "I am raping Frank Herbert" seemed to best represent his view of how to translate the book to the screen.
Weirdly mesmerising: Jodorowsky is bat-shit crazy, but utterly fascinating. It also has a bit of the appeal of a car wreck: you can't look away. And the argument made in the movie that his treatment of the movie was influential in Hollywood despite never making it to film does carry some weight.