This book definitely has a target audience - somebody who hasn’t read anything about theoretical physics, doesn’t want to think about it too hard, but at least wants to know what everybody is talking about when they say quantum mechanics, big bang, or general relativity.
I was not a part of this audience. I’ve read a few pop-science books before, The Elegant Universe about 7 years ago, and From Eternity to Here a few months ago. I enjoyed Eternity to Here much more; it went in to better detail about the mechanics of the questions that the author was trying to answer. A Brief History of Time covers nearly all the same subjects, but in a more general and useless fashion.
The book is too brief, and nearly seems like a definition list of nouns. General relativity is this. Quantum gravity is probably that. Stephen Hawking is a genius professor at Cambridge. But if you really want to understand these concepts, look for a book with equations.