I should start by explaining my opinion of "The Band." I respect them, I even like some of their songs, and I understand how important they were. But I don't love them. I should also mention that I hadn't seen this before and am only now watching it in 2022 (it was released in 1978): which means I had to watch it knowing that it's widely regarded as the best concert movie of all time.
Despite my relatively advanced age, I had to look up most of their guest stars - even some of those whose names they bothered to announce. Van Morrison turned out to be a pretty anonymous-looking guy ... but I knew who he was the instant he started singing. That's a distinctive voice. Others included Neil Young (dear lord I hate that man), Joni Mitchell, Dr. John, Neil Diamond, Eric Clapton, and Ringo Starr (him I didn't have to look up).
I've seen live concert movies before. Not a lot of them, but enough to know they're generally not all that good to look at (or even to listen to sometimes). This is definitely the exception everyone makes it out to be: it was recorded live (mostly - they did a couple of the tracks on a sound stage), but it looks (and sounds) great every step of the way. It's interlaced with interviews with The Band - sometimes them just talking, sometimes with questions from Martin Scorsese (who directed, and was clearly a fan).
The Band knew this was the end of the line for them: this had been set up as their farewell concert. In 2022, the movie feels to me more like a window in time and a brilliant technical achievement than a great piece of music: it was nice to hear some of their best known songs performed live (and very well - they were on their game when this was shot). But it carries none of the immediacy it probably had at the time. I liked it, I didn't love it, and I don't think I'll watch it again.
The 20 minute extra added to the DVD on the 25th anniversary of the event is absolutely worth watching. It mostly has Robbie Robinson and Scorsese talking about how they asked Scorsese to film the event, and then how it mushroomed into this thing with multiple cameras, set design, and something resembling a story line, while their concert promoter decided "if this is an event I'm getting more guest stars" and got some of the biggest and best in the world at the time. And all while keeping it running as a real, one-take concert with a live audience. I've never liked Scorsese's movies, but man, he has skills to bring such an amazing movie out of such a chaotic environment.