A couple of friends of mine and I have been studying up for the theory exam to obtain an certificate in order to receive a ham radio license. The problem is, although the material covered what is required we simply weren't happy with it for various reasons. This book is modeled on the syllabus of what is required knowledge to pass the exam. Whether you choose to use this material as a cram guide, or as a reference is up to you. Each section of the book corresponds to a section in the syllabus, with an additional section at the end to tie the theory together.
You can find a copy of the AOCP(A) Syllabus from the WIA.