This book is aimed at existing C++/Qt programmers and presents ideas and techniques that are too advanced or specialized (although not necessarily difficult), for a first book on Qt.
Qt has now grown to over 700 classes and well over a million words of documentation, far too much to cover in a single volume. So instead of covering everything very thinly, the book focuses on key areas of Qt technology and tries to provide more comprehensive coverage than is available elsewhere.
The book is completely practical in emphasis, with every technique illustrated by working code. The examples show Qt best practices, and have been tested on Linux, Mac OS X, and Windows, using Qt 4.6 and where possible (e.g., using #if QT_VERSION), Qt 4.5. (The examples and a sample chapter can be downloaded from the book's web page. Amazon don't allow URLs so google for "qtrac" to find it.)
The book's main themes are hybrid desktop/Internet applications, threading, rich text handling, Qt's graphics/view architecture, and Qt's model/view architecture (to which four chapters are devoted), although many other topics are covered. Besides each chapter's main subject, lots of other classes, methods, and techniques are used wherever they make sense, to show as many Qt features as possible. So even the most experienced Qt programmer should discover aspects of Qt they weren't aware of, discover new techniques, and be inspired with new ideas.