It's ok for younger kids, with a little bit of skipping over the bad words if you want.
I know a lot of people will say it's not ok because of some of the language, but there really aren't a lot of bad words used. They also seem to be in clusters, so you can just skip over them as well. I watched with my 9 year old and we talked about how Taylor is an adult and sometimes adults say bad words when they're upset or passionate about something, and in all honesty she only caught one of them. I did watch the documentary before watching with her just in case, so I knew where to skip the B**** word, but it's just when she's writing a song, so if your child has heard her album unsupervised, they already know it. I don't feel like sheltering them will help them, so teach them about the words and motives being used. This documentary gives a strong female empowerment to any girl or woman watching and really is relatable in so many aspects. My daughter loved it and loved watching Taylor evolve from an insecure and scared young girl to a woman who runs the music business!!!