Ghouls is a book for the World of Darkness, specifically for Vampire: the Requiem. It concerns humans who are given vampire blood to drink. They become addicted to the blood and, fairly quickly, come to regard the vampire supplying it as the most important being in their world. The blood also gives them access to some of the powers of vampires, making them stronger than normal humans, but they do not suffer the limitations; most significantly, they can go out during the day. Thus, they are the perfect servants for vampires, and that is their main role in the game.
This book thus serves two purposes. First, it develops ghouls in more detail as supporting characters, serving the player characters or their opponents. Some ghouls manage to maintain a precarious independence, and they can be allies or antagonists in their own right.
Second, it considers the possibilities of ghouls as player characters. Bound by their addiction and forced adoration for a master who is normally abusive, they are not in a particularly pleasant situation. However, for a series of roleplaying games that are about personal horror, this is not at all inappropriate. Indeed, I think they would make a very good viewpoint for examining the horror of the World of Darkness.
There is, however, a problem. Ghouls are almost all bound to vampires. This deprives them of the freedom to take the initiative in setting up stories and adventures, and this is a significant limit on a roleplaying game. What’s more, it would be unusual for a vampire to have enough ghoul servants to make a viable group, and even if he did, he would be unlikely to use them as a group. Mixed groups pose their own problems. Mixed ghouls and vampires face the problem that ghouls are active in daylight. Mixed ghouls and non-ghouls raise the problem of why the vampire allows the ghoul to associate with the others.
In short, the problem is that, although I can see how to build good stories around a single ghoul, I cannot really see how to work them into a group. The book does do some work towards dealing with this, and, of course, this is not the primary intended use of the material, so this is certainly not a major problem.
On the other side, however, a lot of the detail in the book is unlikely to see much use unless there are ghoul player characters. The information on how different clans and covenants of vampires tend to treat their ghouls is interesting, but player character vampires get to choose their own approaches. Similarly, the detailed rules on character creation are redundant if the ghouls are NPCs, and will thus be created to reach an appropriate power level. The information on ghoul families may be an exception to this; it can be used to create a new and interesting antagonist for a chronicle, or a background for a character who takes on a role other than ghoul.
In sum, this is a good book, with good ideas that make me want to use it. However, I’m not sure just how easy it would be to really use most of the information given here. If it had that extra bit of information, it might be a great book.