Those guys just did not have any chemistry together, which prevented the film from achieving it's potential. To put people who don't know each other in an contrived situation like that and expect magic I guess is a little too much to hope for. It might have worked better if they had three guys who were real friends beforehand, maybe Page, Beck and Clapton for example.
Their styles are so disparate that I think they found it hard to find common ground. The Edge is very reserved and humble, Jack White is kind of weird and young, and Page is as close to a deity as rock has which makes it hard for him to relate to those guys, even the Edge.
My take from the film:
Page is a rock god, case closed. Not that I didn't know that, but it served as a good reminder. What a talent, he's just jaw droppingly good, greatest riffmaster of all time.
The Edge is has done more with less than anybody in history. He's not a flashy guitarist, but with his use of effects he is able to communicate great power through his music.
I'm not sure if Jack White sucks or is a genious. Probably somewhere in between like most people.
He is a weird sucker, though.
I'd give it a marginal thumbs up, although overall I was a bit let down in terms of my own expectations.
The goal of the film-maker was to look at three guitarists who are very successful and have disparate styles, put them together and see where they intersect and where they diverge. The type of film you suggested he make would have been way less interesting to me. Magic? Sounds like you wanted a Disney movie. (no offense to your position, we just like different things)
IMO, it did a great job of showing that, no matter what the style, if you put 3 disparate-style guitarists together, there WILL be point where they converge (the end section is my fav in the movie). And music IS communication. I lOVED the diversity, but the common element that though they are sometimes saying different things in different ways, they love making music... communicating.