Honestly, this is probably the most frustrating textbook I have ever read (and I'm a bit weird in that I actually like reading textbooks, so...), and I have 2 bachelor's and a master's all in STEM fields, so this isn't an issue that lies with this reader's ability to understand complex ideas. I really had high hopes for this book given the caliber of the authors, and the claim of it being the "gold-standard". Gold standard of what? Poor pedagogy?
Well, why is it so frustrating? It's like the author never had a single proofreader read the book to check for ambiguous, or vaguely worded explanations or definitions. Over and over again, I ran into explanations that have two or more possible interpretations, often this happens in the setup of the discussion so everything that follows is confusing because the author was not careful to make his meaning clear from the start. So you have to expend 4 - 5x more energy (and time) just trying to ascertain what the heck the author meant in the first place so that the following passages can have a coherent meaning, and this can only be deciphered by checking if your working interpretation is consistent with all the statements that follow. And you have to iterate through the possible interpretations until you find one that is consistent with what follows. "Did he mean this? No, no, that wouldn't make sense here. Well maybe he meant this... Or this...?" Like I said, absolutely exhausting. There are even passages where the author sets up new notation and defines it, then uses a different meaning in the following equations, and so there is no consistent interpretation that could make the entire passage coherent, there is an insurmountable inconsistency due to the author switching meanings mid-paragraph.
As Norbert Wiener, the first-class mathematician and founder of cybernetics, said:
“The advantage of a clear statement is that it tends to prevent misunderstandings. But if you are vague, you leave the door wide open to all sorts of misinterpretations, so that by the end of the explanation, the student may well be standing on their head with their feet in the air.”
Ambiguously worded prose, definitions, and explanations are nothing more than unforced errors that destroy the learning experience due to the resulting frustration. There is no excuse for this amount of ambiguity in a textbook whose main edition is in the 10th iteration.
Also, there are quite a few conceptual fallacies in the explanations. Apparently a quantity can be a constant in one part of an explanation but in the next sentence it has to be a (random) variable... Have your cake and eat it too?
The passages are so choppy, most likely due to so many patchwork edits on the many editions over the years. The book needs a serious overhaul by a good editor (and many reviewers), to get the book to a point where ideas are delivered with clarity rather than ambiguity, fluidly rather than spasmodically. I do think a good textbook is buried within, but not as it currently is.
My advice: Don't waste your time and energy; find the "silver-standard" because this "gold-standard" ain't gonna cut it.