I have found this book (and its predecessor edition) extremely valuable to learn Ada.
The author (rightly, in my humble opinion) focuses on the language concepts, which are introduced in a clear and practical manner. He underpins his explanations with plenty of examples to illustrate the usage and syntax.
More advanced material is marked so that the reader can skip it at first if he wishes.
Ada is a very rich language, with its own terminology, and takes time to learn. As with every other programming language, to learn and be able to use it productively one has to eventually accept its terminology, i.e. "wrap your head around it".
The author does not teach avoidance of the sometimes complex terminology, but instead confronts this complexity with gentle introductions to the canonical language references and solid explanations of the important concepts.
In my mind, this is actually a very positive feature of the book. It does a service to the dedicated learner, who - sooner or later - will need to look at the language reference manuals, even if just to clarify some detail. After reading this book and implementing its examples, (s)he will have a sufficiently solid grasp of the language and its terms to do so.
This book was worth every cent to me.