This book covers a lot of information that's already in the Planescape box set but it does a pretty good job of it. It's also handy as a quick reference book if you don't want to go digging through the three books from the main box set. And as the description says, its a good way to help introduce the Planescape setting to players. It contains a lot of game mechanics info which isn't of much use if you're not using the 2nd edition rules but any rule you want to incorporate is fairly easy to modify for a 3.5 campaign. Unlike some people, I think the situational rule changes in Planescape not only make sense but are in fact necessary considering the nature of the setting. You can't go jumping around the planes and not expect physical or magical laws to be the same everywhere. On another Planescape note, a lot of reviewers have complained about cant, the slang of people who live on the various planes. Personally, I think its a great way to immerse players in the world. All of the Planescape books are written as if someone from the game world wrote them, even when describing game mechanics. It helps drive home the point that the world of Planescape is a unique one that has a vibrant life of its own. But I digress...
[5 of 5 Stars!]