I had this book on my wish list for quite a while and finally got it as a Christmas gifts a few years ago. It is a great introduction to deco history and theory. It's written in a pretty approachable style and covers most of the theory that most divers would want. It pretty much answered all my questions about how the tables came to be, and how dive computers worked, among other things. It also helped me understand where the NITOX oxygen clock stuff came from, and why.
As others have said, the only way to get all the information in the past was to read a library of hard-to-find technical and journal papers. The biblio at the back of the book is amazing if you're into that sort of thing.
And for the physics parts, finally a use for all that math and physics from the ol' engineering degree
That said, you *have* to read the explanations and make sure you understand what's going on. As others have said, there are a fair amount of typos, fortunately fewer in the equations. Sometimes it's a typo, sometimes you just didn't follow...
If you're reading this book, sometimes, you'll see A, then B, then C, and you understand everything, then RABID SQUIRREL and you'll think WTF? Where did that come from? I seem to recall that was in the oxygen window sections. For me some of those were places I just didn't understand at first, but a few did turn out be be typos.
This lead me to re-read the book a few more times with a calculator and laptop nearby so I could check the formulas and math

It was an interesting way to read a book.
That said, THIS IS A GREAT BOOK! I will continue to recommend it to anyone who wants to know more about "why deco?" and "where did the table come from?" and "how does my dive computer know?" Also great for students of a technical bent who want to "do the math", or at least understand it.
By the way, if you've got a STEM-tracked or GATE or other math/physics-inclined high school student who is a diver or wants to be one, this would also be a great gift.