In one of the DVD extras, an interview of Michael Apted conducted by Roger Ebert, Ebert recalls reading an internet user's response to watching all seven films in a 24-hour period. This person said it was a metaphysical experience. It wasn't about seeing the lives of these people, but it was seeing life itself.
I cannot disagree with this statement. I was powerfully affected by seeing the growth of these people, the way they age, their hopes for their own children. Even the ways they interact with Apted and with the camera become riveting -- especially in this latest edition, where the established relationship that many of them have with the director is allowed to play out on the screen for us. Some of them are angry at him for the way they've been portrayed (or mis-portrayed).
It's really hard to explain the impact on me. I don't watch the film merely reflecting on these people's lives (though I do that as well). I watch it and think about how my life is so much like theirs. Not in the details, but in the arc of a life in general -- the ways in which we are the same.
Please watch it. You will be glad you did.