Lanzmann's journey to understand how this could have happened is exactly what was needed to be put to film. Lanzmann comes at the topic from every angle he possibly can. It consists of interviews of survivors, bystanders, and even perpetrators! It's the most thorough investigation into the Holocaust that has ever been made.
Shoah is a testament to the worst of what humans are capable of. Inaction due to ignorance, hatred, fear or any other reason lets this happen. And it is up to humanity to never forget and never let it happen again.
I honestly can say that I didn't get to comprehend the extension and meaning of the Holocaust until I watched this 9h documentary. Probably, I still don't even get to be close to its understanding now but this has been clear to me after watching the movie.
This is the kind of historic document with incalculable value to leave proof of what happened during WWII so nobody can really put it in question. I would even say that this movie should be passed in history class in high-schools all around the world.
The work done is huge and, although I would say that, at some points, I don't understand why Lanzmann makes some kind of trivial questions, I reckon that the actual purpose is to make the viewer to understand all the aspects of the happenings: the extraordinary and the casual usual ones.
A must to be seen, if you feel strong enough to face the terrible truth and fate of millions of people.
Oddly, "Shoah" isn't a masterfully structured narrative -- not even its episodes are necessarily chronological. Although some subjects appear through various parts of the film, there is no through-line, no single subject to relate to through the film's length.
That said, this is a phenomenal record of history -- both of the holocaust and incidentally, life under Communism in late 70s / early 80s Eastern Europe where many of the film's interviews and extensive footage is shot. The quiet establishing shots of this dark history's locations -- 30 to 40 years later -- are at once haunting and beautiful. The subjects' stories are profoundly moving, but somehow not overwhelming -- they often speak coldly, decades of practice suppressing their emotions, many of them having suffered unimaginable guilt for their relatively good fortune.
"Shoah" is a film to be seen. Do it.
This is a must see for all mankind.
I expect that the running time was more effective in the mid-Eighties when the film was released and these stories were a revelation than it is now when most of us have been exposed to many, many details of WWII that were less easily shared in the decades closer to the war.