Got mine yesterday. I haven't had a chance to dig into it that much, so I can only give a limited review and general impressions.
Before I do that, let me say up front that I'm not a lawyer, and am not able to judge any of the legalities regarding copy writes, etc. So I'm simply not going to "go there." In the interest of full disclosure, I am a regular visitor to startrekhistory.com, am on their mailing list, express my great appreciation for all that they do and hope they continue to enrich our lives with their efforts. I do note that the book lists that site as a resource in the back, but whether the authors "lifted" information illegally or inappropriately is beyond my ability to discern.
That said, in the limited time I had to read last evening, I concentrated on one of my favorite episodes of the first season, "Court Martial." As you've read above, there are a number of interesting aspects throughout the script development, production and post-production that I have never known about. That certainly sells the book for me, as I'm as interested in the production of the series as I am about the final product.
As to factual and grammatical errors, I haven't really found any yet but I'm not really looking that hard right now. I'm satisfied in the accuracy because the author (1) was given access to the original files created by the producers and (2) conducted a number of interviews with those involved, including producers, directors, crew, actors, etc. Justman's enjoinder--(paraphrase) 'The memory fails, but the original docs never do'--is a good thing to keep in the back of your head as you read this book and come across things that contradict what you think you knew.
Now comes the big challenge for the authors as far as I'm concerned: Season 2 (release date, anyone?). That's where most of my very favorite episodes reside. Of course, I most look forward to learning new things regarding my all-time fav, "The Doomsday Machine." The foreward to this book states that William Windom and Norman Spinrad were interviewed as part of the overall project, so I hope to gain more insights than I ever have regarding this episode.
Do I recommend this book to you? Yes, like I'd recommend you continue breathing. BUY IT!