The first episode just aired yesterday, so obviously my review isn't my final, overall opinion. I just wanted to address the reviews that gave the first episode low marks. It seems as though the reviewers don't realize that this is a documentary series in 6 parts. There's more to it than just the first episode, therefore, the entire story is not going to be told in the first 60 minutes.
I don't think it was disjointed, as others have said; I think it does a good job of laying the groundwork for the rest of the series to build on. And yes, there is a focus on Michelle McNamara, the author of the book. The full title of the book is "I'll Be Gone in the Dark: One Woman's Obsessive Search for the Golden State Killer," that indicates that some of the documentary is going to be about her search, along with the EAR/ONS's crimes.
I read the book recently and I'm excited to see how this series unfolds, partly because there will be interviews with people who were involved with the original investigation, along with interviews of victims as well. Ms. McNamara interviewed people for the book, but to be able to hear it directly from them should be interesting. I just hate that I can't binge-watch it all at once!