Although I've read Pullman's trilogy, I'm not familiar with the stage adaptation beyond having browsed the tantalizing production pages that were once on the National Theatre's website. I'd hoped that this book would have similar content, with in-depth explorations of how the actors view their characters, what changes had to be made from the original text, perhaps some pix of stage scenes, and so on. Instead, this book seems to be a rather superficial summary of the pre-production process and seems to be written down to its readers, with passing references to Kenneth Branagh and Zoe Wanamaker only as "Gilderoy Lockhart" and "Madam Hooch". Although there are plenty of photos, all of them are black-and-white and most of them are of things like informal rehearsals and the design/construction process for props and costumes.
Perhaps I'm simply the wrong audience for this book, which might be hypnotically fascinating for people who actually work in theatre. However, I still think it doesn't make much sense without more knowledge of "His Dark Materials" as a staged play, whose adapted script(s) by Nicholas Wright I hadn't realized were also available and will probably buy next.
Because of those allowances, I'm giving this book one extra star from my original impression: since its focus is on pre-production rather than the finished play, it seemed like, well, all shallow foreplay and nothing more. It really doesn't seem complete by itself, as if it were a severed daemon wandering about lost and alone.