I have been going through Chapters 1-3 over this past week. The book has been excellent. I really like the key topics for note taking. After reading the chapter, I go back over the key topics and first relate them to what I already know, and then describe and explain them both mentally and in notes.
As Scott said, the first chapter was a bit heavy. Some of it was already familiar from Security+, but the Cisco book greatly expanded on general security concepts and different types of attacks. I have IP Spoofing and source routing down. In Chapter 2, I am learning the Risk formulas, and in Chapter 3 becoming familiar with the different router models and specs.
I am taking a Microsoft MCDST test this next Friday; it is not particularly difficult, so lots of time will still be spent on CCNA Security
Chapters 1-3 should be down pat by this Monday.
Thank you again for this exciting opportunity.