As an adamant fan of astrophysics and all things cosmos, I got sucked into the proverbial black hole that Stephen Hawking had created with the book A Brief History of Time. However, fairly early in the book, I nodded to myself, agreeing with the consensus that the book can be a challenge to people without a physics or cosmology background. Trying to conceptualize imaginary time on top of hearing about imaginary numbers for the first time may be overwhelming for some people.
Stephen Hawking wrote the book for the general, non-technical audience. Be that as it may, I found that the concept and theory explanations are inconsistent in their delivery, as if there were missing pages sometimes. Things like geodesics and great circles are accompanied by illustrations, whereas the reader is left to imagine concepts such as imaginary numbers and imaginary time.
The first edition got released in 1988, so the book has had a long time to build its legacy. Along with that legacy also come the discoveries and phenomena that were theorized or observed indirectly back then. Gravitational waves, for example, were first directly observed only in 2015 by LIGO. It is possible to trip over the facts that are no longer entirely true today. The book explores the scenarios in which the Universe is contracting, expanding, or static. However, in 1998, ten years after the first edition came out, it was discovered that the expansion of the Universe is accelerating. Unfortunately, this fact is only mentioned in the book's appendix (I read the 2016 edition).
Overall, do not expect an easy read. A Brief History of Time will leave a lasting impression if you're willing to dedicate quality time to it. The book is slightly dated in its original form, and you are required to read the appendix to stay true to the facts.