This book provides a very nice preparation experience for its associated exam. Like the previous edition for .NET 3.5, the WPF coverage is quite good, though more limited. Due to changes in the scope of some of the Microsoft exams, the one associated with this book include both Windows Forms and WPF, meaning that there is less WPF coverage here than in the previous version. As such, for WPF details, I'd recommend purchasing the prior version of the book (for .NET 3.5) if you want a comprehensive review of WPF features.
The inclusion of Windows Forms in this book, though it displaces some WPF material, is fairly comprehensive and integrates well with its mirror WPF material. It's very helpful seeing a WPF technology and its associated Windows Forms counterpart. These parallels illustrate how Windows forms technologies have continued to evolve and incorporate some very useful technologies, such as property bindings and interaction with WPF elements.
One worthwhile point to note is that this book is not quite comprehensive for the exam, as prior versions have been. Again, this owes to the fact that Microsoft re-scoped its exams, including Windows Forms, WPF, and application security in this exam (amongst other topics). While the material presented in this edition covers WPF and Windows Forms well, there are a number of topics that are either glossed-over or not present, but are addressed in the exam. These topics can easily be supplemented with some reading on MSDN, however, and their absence does not diminish the usefulness of the book.
Surprisingly, there are very few typos and / or errors in this edition. It's a pleasant surprise given that most editions have at least a few incorrect statements. The practice tests are on-par with those of other Microsoft Press exam kits, having a few errors, but nothing that isn't immediately noticeable and worthwhile in that it prompts additional reading.
I recommend this book to anybody that seeks to prepare for the exam. However, I caution you that unlike other exams and preparation kits that cover all the material quite comprehensively, the breadth of this exam makes a single research book a bad idea (you would be at a borderline-passing level with just this book). At the very least, review materials on MSDN. If you want to cover everything for the exam, this book in conjunction with either the Microsoft Press 70-536 and / or the 70-502 training kit(s) should be about right to give you a good margin on the exam.