Neil Young looks crazy during the finale, like some guy you'd see on a street corner and walk around an entire block to avoid. Joni Mitchell seemed uncomfortable standing next to him. But his performance was good.
I think the movie is a great concert film despite the awfulness of the interviews, but I do think the other members' later criticisms of it as giving Robertson too much of the spotlight are fair. I already mentioned that he's singing into a dead mike, and there are alot of shots of him doing it.
I don't think it's all that weak that their reputation rests on the first three albums. They really only had 5 "normal" albums, so three classics is pretty good.