JavaServer Faces by Hans Bergsten (O’Reilly)
The book really digs deep into the JSF API. It starts off with explaning about HTTP, Servlets and JSP and then gradually moves on to JSF by starting off with an example. Then the book keeps building on the example while explaining new concepts. As always, Hans has had a very detailed approach in explaining the various concepts. However, as compared to the Core JSF book, I would recommend the Core JSF book for somebody who wants to start off on JSF, and then move to this book for more API specific stuff.