This book is definitely intended for the network admins who are running (or hope to run) some sort of PPP-related service. The book explains how PPP connections work, from PPP packet header information to network and routing setups as well as debugging them. The information is very detailed and comprehensive, and well-written.
A user who just wants to setup a modem connection from home will probably find this book is not for them though. The topics covered focus more on using the PPP protocol in a network setting, rather than just a home computer. However, the chapter on setting up a dial-out modem does show a home-user how to setup a modem connection on several operating systems, and answers questions that even modem "veterans" like me have. :)
In closing, this book is well-suited for network admins, but regular users should find a book more suited for home use. However, I think this book has something for everyone interested in PPP.