I watched this last year as part of my ongoing quest to watch more classics. It was 36 in the previous list and I'd read a few things about it and so steeled myself to sitting through 3 and half hours of French avant garde tedium. But I was pretty impressed, and reading some of the films biggest fans talking about it helped me appreciate what the film was doing. Delphine Seyrig, as you say, is remarkable.
I love lists whilst appreciating they are an inherently silly thing when talking about something as subjective as art. Primarily they exist to generate discussion, but also to help introduce people to things they might not normally have seen. (Something they have in common with our own film club)
I like the Sight and sound list especially because it's been going for so long and really shows the evolution of criticism and the evolution of film critics. The best thing they have done is expand the roster of film critics they ask to contribute. in 2002 they asked 145. And I don't thing it's unfair to say the majority of them likely were cut from a very similar cloth. In 2012 they expanded to 846 and this year it was 1,639, and it's a much more diverse group of film critics. But they are still film critics, people who spend their time watching a lot of film, studying cinema, and I think the best way to enjoy a lot of the earlier films at least is to watch then seek out writings on the film. I find it much more rewarding when someone much smarter then me explains why the film was so good in the context of the time it was released.
If nothing else it's bumped Beau Travail well up my list of films to finally catch up on.
Alex