Comments about oreilly Designing Gestural Interfaces:

A very designer-oriented book, but quite elementary for those of you who have had some experience in designing interfaces. Dan Saffer presents in his work, a comprehensive collection of gestural resources, the science of kinesiology, ergonomics and physical computing to deliver patterns in gestural designing. The book is quite easy to read, with the author logically setting out the processes involved in prototyping and documenting how the user should interact with the device application, in an intuitive and anticipative way.

The author looks at how other devices and technologies deal with problems and how various gestural solutions can help alleviate otherwise complicated means of achieving a resolution for the user. The author does also look at future trends, but with it being a late 2008 book, it may be a bit outdated by now. It does however present a good understanding for novice mobile UX designers, to comprehend the principles behind the design, but a revised edition showing the current 2012 trends would be invaluable. There are so many apps out there that have gone against normal patterns, yet are gesturally intuitive, which would be worth adding to this book.
The content itself is great in terms of width but in terms of depth, lacking. It does not provide great detail on problems and issues but rather refers readers to other literature throughout. It leaves you feeling that you need an advanced book on understanding in greater detail the solutions to problems, rather than just identifying various problems that are prevalent across multiple platforms. I think even a specific iOS book that examines actual problems and solutions, would be warranted, by going through issues in contemporary iOS applications and overlaying them on top of what Dan Saffer's overview book has on gestural pattern design.
Overall, I give this book an amicable 3/5, for a novice designer, but for the more seasoned ones, I'd hold off on getting this book, unless you want to brush up on some elementary information you feel you somehow skipped during your career development.