The answer is easy: Because it teachs C++ the way C++ should be taught.
Why re-invent the wheel if there are a lot of wheels available for you to use? Why learn to do things in "the hard way" if there is a lot easier ways to do?
C++ should be taught from its C-inherited no-more. In C, we used to do something in "the hard way". For example, just to use string efficiently, one would need to understand pointer properly, since C-string is pointer to char (char*). Just to dynamically store some instances of the object (to store the objects "as needed"), one would need to know how to manipulate pointers, which always lead to problems and confusion, to imprement the dynamic container.
And that's what almost all other C++ books try to teach you "first". And they will teach you what should be taught ealier "later". You, by that way, it takes longer to be productive, or even to be an able programmer.
Then, how C++ should be taught?
Bjarne Stroustrup, the father of C++, said clearly in one of his paper, named "Learning Standard C++ as a new Language", (available in his homepage) something like "Learning a programming language should support the learning of effective programming techniques. My favourite approach is to start teaching the basic language (variables, declaration, loop, etc...), together with a good library". And this is exactly the approach taught by this book.
I, personally, agree with the previous reviewer that with the approach used in this book, pointer and array are easier to understand than learning from the traditional approach.
Learning C++ from its standard library aspect can make you a productive programmer in much much shorter time than learning from the traditional approach, which begin with C-subset, and many programming techniques that you have to "unlearn" as you progress on.
In case that you're wondering how much you will learn from a book of this size. All I can tell you is, more than you can ever imagine. However, you will have to concentrate on what it's saying. And then, after you finish this book, you will have no (or almost no) problem when moving on to the more difficult (say, more advanced) books like those by Stroustrup, Lippman, Musser & Saini, Austern, Josuttis ... etc (all are my personal favourites).
The wheels had been invented. So why not just use them?
In short, this book is nothing more than the BEST book on introductory C++ ever written, period.