Actually 4.5/5, just rounded down for goodreads scale.
The in-depth details and images would have made this already essential, but it's also assembled by Castle with such thorough chronological background that makes it a great read. However, this would have been full 5/5 for me if not for two issues:
1) Each film has a central essay detailing from its conception to its release, so I was anticipating the one for 2001, only to disappointingly find out that it's the only one that breaks away from the format, and is composed of timelines and disparate essays on different elements of the film instead.
2) From Barry Lyndon onward until Eyes Wide Shut, each film's central essay is by Rodney Hill, whose writing is tad too hagiographical on Kubrick for my taste. For example, the theatrical release part of his essay -- on every single Kubrick film he writes on -- always points out how Kubrick's films were misunderstood upon initial reception by some circles, preemptively dismissing the criticisms by bringing up praises from critics who "get it", which gets eye-rolling by the third or fourth time he uses this already.
Also, I was looking forwards to reading about the treatment of Shelley Duvall on the set of The Shining. Considering the involvement of his estate and family with the book, I didn't expect that section to be seriously disparaging towards Kubrick or anything, but past essays haven't shied away from mentioning the frictions or differences Kubrick can have with other actors, like Spartacus (Kirk Douglas and the film's British actors) or Lolita (Shelly Winters). But all Hill mentions, in a positive tone, is why Kubrick casted Duvall for the role, which feels crossing the line from too hagiographical to borderline dishonest for me.
This is still engrossing in details and gorgeously put together though, even through sections of Kubrick films that I'm not a big fan of (eg. Lolita), so that I'm very glad I blind-bought it.
Trivial side-note: this book has a ton of BTS stills, and as I was reading through it, I was curious to see Kubrick's switch from his early, relatively fresh-faced look to his more common, older bearded image in later career. I know it's an age thing, and the film's production took over a few years, but it's funny to see from the pictures how most of that transformation seems to take place primarily over his time on 2001.