This 1400-page monster assumes absolutely zero previous knowledge of information security, cyber security, information management, risk management, information assurance, identity management, practical cryptography (types of ciphers and modes of operation: no formal proofs of security, no math nor theory: just read the NIST Special Publication 800-series docs, like 800-90 on CSPRNG, and for the math Goldreich's Foundations of Cryptography in 2 vols.), or any sort of development or engineering and only a basic familiarity with technology.
This means that anyone who is in a position to pass the exam after reading this book could have done with 600 fewer pages of introductory exposition. The book is, like many technical works that aren't mathematical, both too long and too short. It's too long for someone with experience in engineering, but too short to descend into the weeds past generic applications of the abstract principles of the '8 domains of the CISSP Common Body of Knowledge'.
The 8-volume, outdated Information Security Management Handbook of 7,000 pages goes into great detail of every application of every domain. CyBoK, the European work, is more practical and engineering-oriented, but of no relevance to the credential. Thanks to the influence of the credential, the practice of security in real life is often divided along the same lines as the exam. The CISSP CBK [Common Body of Knowledge] Reference is more detailed and shorter, nondidactic but sufficient for anyone who can solve a leetcode easy to learn the jargon and style of (ISC)2's CISSP.
It's said the CISSP is a management credential and also useful for government work. I wouldn't know, but it's pretty universal on the security side of the house at tier-2 corps for engineers, architects, security officers, and so forth, and common at tier-1s among middle management and GRC people. It's certainly not an engineering credential because it will teach you little of secure development or secure architecture but much of security tradeoffs.
I got one of these back when the exam had 10 domains and was on paper, but here's the only advice you'll ever need: The exam is nothing like the book. It is less technical and much more ambiguous, with few right or wrong answers, and full of convoluted phrasing and 'gotchas' in the same class as double negatives.
Consider it practice for email threads with non-technical people when you become an engineering manager. The cert is worth it for middle engineers (not junior, not senior) with an interest in systems security, anyone who has a job that pays for it, and for people who want to become managers without getting an MBA.
Vagabond of Letters, CISSP-ISSAP/ISSMP