If the players, excluding the GM, have to get only one book, this is the one.
The book is very useful if you don't have or plan to have all the previous books, because it regroupe every careers published in the previous WFRP2 books into this volume. The Career Compendium give to the players a total access to the career available to them to create their Personal Character (also useful for the NPC creation). This book give them a great autonomy to plan and build up their characters. For the players, this book is then more useful than the Core Rulebook. The book include, also, the career published in the late sourcebook Shades of Empire. The Career Compendium is good for all the common set of Personal Character. It regroupe all the career used and available for a standard campaign of WFRP2. It gives more information about each career and includes, also, some new one.
The official pdf scan for the Career Compendium is extremely well made. It is very clear, with no blur marks. The images resolution is very good. I find it better than the one used for Tome of Corruption and Tome of Salvation. It offer the same resolution quality found with the official pdf for Night's Dark Masters. (Note that the official pdf for Tome of Corruption and Tome of Salvation are, still, extremely well made. If you plan to purchase them, you can do so with the assurance to have a pdf of good quality.) They have, also, included useful Bookmarks in the pdf, such as an alphabetic order to have access quickly to every career.
It doesn't regroupe the most exotic career such as those found for the Skavens and the Vampires characters (you do have the career available for the humans and other common PC offered by these books such as the Slave, the Agent of the Shroud and the Killer of the Dead to name a few). You won't have those specifically linked to the worship of Chaos such as the Chaos Champion career path and the Cult Magus of Khorne, for exemple. You do have some of those linked to the Norse, such as the Marauder, the Whaler, the Seer and the Warleader, since they can be played more easly in a broader set of campaigns.
The new illustrations for the career who didn't had one originally, such as the Warrior Priest found in Tome of Salvation, are very well made and are a great add on.
It offer numerous useful synthetic tables such as one that classify all the career available for each races specifically.
The adventure hint given for each career are amusing and useful for the DM. They can help you to build up small adventures and to construct starting lines for scenario that would put the emphasis on a selected career.
Whatever if you are a DM or a Player, this book will be useful for you for the numerous information it include and for it conveniency.
[5 of 5 Stars!]