I haven't read any of the other two books, so I cannot tell you how this book falls into the greater scheme of things. I.e. I do not know what sort of overlap exists with the RUP Intro book, or which of the two to read first, etc. What I can tell you though is that this book, as it stands on its own, is a very good book in helping you (a) understand what the RUP is and (b) understand how to apply it on your projects.
First of all, the two authors of the book are as authoritative as can be. Kruchten (the author of the Intro book) is the chief technical RUP guy in Rational. Kroll is the Rational director (or whatever his new title is now under IBM) responsible for the RUP. These guys know the RUP and in a sense _are_ the RUP.
Now, to focus more on the book per se, it is as follows: It starts with a general intro chapter and then it moves on to chapter 2, which captures the so-called "Spirit of the RUP". It contains 8 tenets which sort-of summarize the philosophy of the RUP. Just as with a legal system, where it is not sufficient to only know articles of laws and statutes but you have to be extremely familiar and cognizant of the context in which these laws are applied and the purpose they serve in order to judge correctly, similarly with the RUP you don't only need to know the product with all the info and features it provides, but you need to have absorbed the philosophy that governs the process in order to apply the given material in the appropriate and most fruitful manner.
Chapter 3 I found (the emphasis is on "I"; you mileage may vary) the most useful. It basically charts the whole territory of processes that are out there (RUP, XP, other agile processes, heavyweight assessment standards such as the CMM) based on two important criteria, and tries to make you understand where RUP falls in the plane (and it is not really a fixed point, as RUP is customizable so there is some sort of leeway in how much iterative and/or ceremonial we want it to be).
Chapter 4 is an aberattion to the rest of the book IMHO, and I haven't found it much useful, or to my liking. It basically tries to explain RUP phases etc. in the context of a one-man project. I am not saying that this is necessarily a bad way to try to introduce people to the concepts of RUP in a more practical context - maybe you'll like it; I just didn't.
Afterwards, in chapter 5-9 we have an expounding of the 4 RUP phases, while chapter 10 is product-specific. Chapter 11 is extremely important as it talks about how to adopt the RUP in your organization, and proposes as the way to do so, treating the RUP adoption as a project of its own and applying some sort of "meta-RUP" on it; very interesting! Chapter 12 talks about planning an iterative project and Ch. 13 covers "antipatterns" (although the authors, to their credit, avoid using that term). Ch. 13 is very important reading and some of the stuff in there (e.g. the discussion on what constitutes a bad use case) you will find useful in a context much wider than the RUP.
Because each one of the roles (PM, Architect, Developer, etc.) views the process from their own unique perspective (just as power forward views the ballgame more in the perspective of getting many rebounds, whereas the point guard views in the sense of passing assists and shooting the occasional 3-pointer) it is very useful to have a chapter discussing each role's unique perspective of the RUP. My opinion is the all roles must read the chapters for all roles, but if you are short on time, this also helps you focus on the stuff strictly pertaining to your role. Although I am not a tester per se, I liked very much the discussion on "Good Enough Quality" in the Tester chapter. "Paradigms of Good Enough" and "The Cost of Quality" I have found to be a "must-read".
Also, the book has good references (both books and Web articles - especially from the RationalEdge) and the usual good quality you would expect from an AW publication in general and an OTS book in particular. Finally, even though in the intro the authors play a little pun on themselves on being French and Swedish respectively and thus non-native English speakers, don't get scared by that comment. Their English is excellent.
All in all, a very good and useful read. Buy it if only for chapters 3, 13, and 18. Actually, you may want to buy it even if you are not intending to use the RUP.