I bought this book for 2 reasons: I had tried to use GRASS for vector data processing - with mixed success - in the past, and wanted to gain a better understanding of its capabilities; and also because I had just been assigned some fairly difficult elevation data processing, and raster-based spatial analysis was something I had little experience with. The book succeeds on both counts. It has well-written explanations of basic GIS principles, and also describes operations in enough detail that one can replicate them with their own data.
While an amazing GIS application (I would actually call it a "GIS environment"), GRASS is not without its quirks. The book does a good job of steering a reader around potential roadblocks, and focuses on getting one going about the business of doing useful work. For example, they recommend using the GUI to set up a project, but then have you move back to using the command line interface (CLI) and X-based display window to accomplish the bulk of the work. This is brilliant. It showcases the ease with which GRASS commands can be chained together, and how other UNIX commands can be interleaved in the command sequences. Make no mistake, this book is written for an audience that is either familiar with, or willing to learn some UNIX. That alone makes it a refreshing change from many other books which feel apologetic when they stray away from the apparent comfort of a MS Windows-based GUI. GUI's are mentioned, but only briefly, and not in a way intended to be a useful guide. People looking for how to use GRASS via a GUI'd application would be better served by Gary Sherman's "Desktop GIS" book, which discusses how to use GRASS through the excellent Quantum GIS application.
The book is logically laid out, and generally well written. There are a few small grammar quirks which tell me that the authors are not native English speakers, but they are minor, and don't actually cause the reader to stumble over any sections. Code sections are well-defined by the use of a different font, and so far I have not encountered any that contain errors. The book is well-illustrated, although at a cost of over $90, I take issue with the lack of color. This is a topic related to cartography after all, and color matters.
I highly recommend this book to people who want to learn how to use GRASS effectively, or to teachers who want to structure a GIS course around an open source application. There is enough GIS theory presented to teach an intro-to-mid-level course on GIS. GRASS gets a bad rap from many in the GIS profession, and this book should allow most people to get over the initial humps and get started with it in an effective way. Hats off to Neteler and Mitasova.