I read this for a class that I took, and it wasn't as useful to me as I might help. While it covers the basic concepts of Network Perimeter Security, as it goes farther in depth, it misses the sweet spot of more specific information versus tool-specific advice.
My feeling is that any written book needs to be careful when giving tool specific advice, providing me examples on how to set a specific CISCO router is useless if the industry has moved beyond using that router - therefore, it renders much of the book less than useful as, at the moment, I'm not sure what environment I'll be put in.
However, I did find the award winning network perimeter examples/case studies to be quite useful when conceptualizing an "ideal" perimeter. Overall, if you've got the cash to burn, pick up the book, especially if you are newish to the field (like me!), but don't expect it to stay on your shelf for frequent referencing.