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.
Will say due to its length you should invest alot of time into watching it or break it into smaller segments, come might call that a bad way to watch it but whatever it takes to let people watch it.