This book is an excellent introduction to the work of Franz Brentano, a founding phenomenologist who served as inspiration for Husserl, and later Heidegger. The book provides a short sketch of his life, and chapters on the basic aspects of his philosophy (starting with "scientific psychology" and progressing to metaphysics and theology). Finding English-language work on Brentano is somewhat difficult, so this book is already a rare find -- but more so because it is well-written, informative, and highly readable.
Beginners at Brentano should know that the book does assume familiarity with some concepts (e.g., Aristotlianism, phenomenology, etc), as well as some major philosophers who influenced Brentano. The writing is rather dense, but not as dense as most serious philosophy books. The topical project of this book is the broad "For Dummies" type introduction to Brentano, but it is written at a much higher level.
Overall, this is a short, and extremely educational introduction to the thought that inspired Heidegger and others. It does not go into great depth, nor is it very easy reading, so it's probably best for someone with a moderate amount of knowledge in this field -- it may be too basic for experts, and too difficult for novices.