I'm a huge "Back to the Future" fan. I ravenously absorb every morsel of detail surrounding those movies that I can. I was anxiously awaiting this movie to give me a deep dive behind the scenes of my favorite franchise. Instead, it's mostly a series of puff pieces about various BTTF fan groups, Delorean customizers, & charity work. Now, I'm not knocking any of that stuff. They seem to be doing good work. But it's just not that interesting.
For what it is, it's very well made. It's well shot & edited. The sound is good. Some of the music is great, especially the acoustic guitar version of the main "Back to the Future" theme played at the beginning.
I guess it's just that I was expecting "Hearts of Darkness" and what I got was more like "Trekkies." Now, if you're interested in a real in-depth look at the movies themselves, I recommend "We Don't Need Roads" by Caseen Gaines-- https://www.amazon.com/We-Dont-Need-Roads-Trilogy/dp/0142181536/ref=sr_1_1?keywords=We+Don%27t+Need+Roads&qid=1565304777&s=books&sr=1-1