I saw it, and thought it was pretty awesome. Very interesting, and a lot of fun to watch. It was great to hear what his dancers had to say, because most of them grew up idolizing him, since he is one of the greatest dancers who ever lived. They were thrilled to be working with him. The only downside was that he sometimes did not sing the songs the whole way through. He was trying to save his voice for the concerts. This film was not intended to be the final product, the concert was, so some of the performances are incomplete because they are rehearsals.
As MJ was such a mystery, it was fascinating to see what he was like while he was working. He came across as very professional, respectful, and serious about his work. Also, it was inspiring to see him perform the old songs. In recent years, looking at him almost made me want to cry, because he'd destroyed his face and become a shadow of his former self. But seeing him perform Billy Jean, you could see some of the magic still there.
It's such a shame. I would have loved to see this concert live.