12 colleagues and I were doing the CISSP simulataneously. Between us 4 different books were ordered. I tried them all, and the difference between this one and the rest is indescribable. On numerous occassions someone would walk in pulling their out having tried to understand a topic in their book. "Can I please see your Shon Harris?" would inevitably come my way, followed by "oh right. Now I see." The CISSP subject matter is vast and it takes an amazing person to provide sufficient, well structured, well summarised, background information about a subject before delving into the security content relating to it -and then describing that in such a logical and easily understandable way. Thank you Shon. I wish you'd write more stuff.