I own a copy of C++ GUI Programming with Qt 4 and I am very pleased with the book. I have had no other introduction to Qt other than this book and the help of the members of this board when I have questions (#Qt on irc.freenode.net is good too). The book assumes you are familiar with C++. I am far from even an intermediate level and I find the book easy to follow. A broad portion of topics are covered in the text, although I wish there were more examples with more detail in parts, but the book is only ~450 pages. Overall, this book is very good. When I am writing the programs I am now working on this book and the Qt docs are both open. I would like to find another Qt book that is more of a reference. The Qt docs are very good but as a beginner I feel lost when trying to follow them sometimes.