This book is light enough to be read in one sitting. And, given how important Facelets is to JSF development, is a worthwhile read for any JSF developer. (Note that this book is focused primarily on Facelets - and by extension takes familiarity with JSF for granted.)
The upsides? I found very broad coverage of everything that Facelets provides. Whether its templating support, the jsfc attribute, the EL, extending Facelets with custom tags, etc. ... its all in here.
The downsides? Trying to cover so much ground in 80 pages is a losing proposition. As a result, some topics are covered in detail, whereas others seem to be included just for completeness sake.
The difference in writing styles between the two authors is noticeable - and some chapters (like the earlier ones) are treated much better than others. I can't imagine why a short book like this one might have merited more than one author.
The high point of this book is in its first chapters - it provides good information on how to setup Facelets (esp. the libraries you will need), and provides a very well presented introduction to its templating support.
However, shortly thereafter you run into the Facelets Tag Reference chapter. For over 15 precious pages, the Facelets documentation is re-packaged with very little value addition.
Bottom line - this book tries to be much more ambitious than its short format will allow it to be. In some places it succeeds, but in most others, it tends to be constrained by a lack of space.