I must preface this review by firstly saying that a copy of this book was provided to me free of charge to review and secondly I am not a developer. I would also say that in many respects the demand for such a book would be limited given the current poor penetration of Windows Phone 7.
That said the book does achieve what it sets out to achieve, basically. I view this book as more of an introduction of what is possible rather than a deep dive into creating Windows Phone 7 SharePoint applications. My expectation was that the book would focus more heavily on the Windows Phone 7 application development but it was disappointed that it spent a significant amount of time running over the basics, especially of SharePoint.
As a general introduction to both Sharepoint and Windows Phone 7 I think the book really hits the mark, especially when it comes to Windows Phone 7. However, I felt that it should go deeper, which may be an incorrect assumption on my part. I am left feeling that there is so much more that could be achieved but this book doesn't quite take me there.
I would certainly commend the book as a great introduction to Windows Phone 7 and what is possible when combined with SharePoint. However, I'm puzzled by which audience it is aimed at. If it is developers then the book probably doesn't go deep enough. If it is for SharePoint users then the Windows Phone 7 parts add a distraction.
In summary, the book is an excellent introduction to the world Windows Phone 7 and the integration possibilities with SharePoint. However, it is not something designed for the hard core developer looking for a deep drive technical reference.