Very entertaining and informative. The thing that really sticks with me about it is the perspective of an astronomer in this situation. He repeatedly was able to get further with his investigation because he logged everything that happened in his computer "logbook." He learned to do this because in astronomy, if you didn't write it down, it didn't happen.
It's also kind of amazing how lax security used to be in serious network environments. I guess that's both a good and a bad thing. It's good that people were more trusting (perhaps because people were more trustworthy?), and bad because it finally got taken advantage of.
The computer logbook he used in this book inspired my Chiplog. Old school command line Unix hackers can really get some stuff done with no fuss.