I teach classes for computer professionals in UNIX. One of the courses is a 2-day class in unix security, and the "Morris worm" is one of the case studies we discuss. We don't go into too much detail in the class on the subject, and I usually recommend this book for those who want to go further.
The other reason I recommend this book to students in my class is the story (in Kevin's section) of Susan Thunder. The concept of "social engineering" is one that transcends computer model, operating system version, etc. Many computer types just don't understand it, in the same way they don't understand office politics. If you fall into this category, or if you have an interest in the social side of hacking/cracking/phreaking, Hafner and Markoff do an excellent job of presenting these concepts.