It's hard to rate this. The actors and crew clearly love the project, and that's commendable, but the finished product had so many issues, and it's hard to look past that while watching this documentary.
Watching it also made me aware of some things that were cut from the show, that would have made it so much better: Sylvie having Loki-like hair, Kang attesting to his own omni-presence, etc. I wish the showrunners had been more mindful about these omissions and how massive the gaps would then be for the viewers.
And the documentary totally glossed over what was, by far, the best part of the show: the score. I could watch a whole documentary on that part alone. Yes, the show is largely style over substance, but the score is full of both. The score is flawless.
I will add, Tom's voiceovers in the documentary were a smart choice, and worked well to bring overall cohesion, thoughtfulness and charm.