I was disappointed with this book. I have about 10 O'Reilly titles, mainly Perl-related, and I guess I expected more from an O'Reilly book. At over TWICE the US cover price, we pay a hefty premium for technical books in Australia, so I don't like to spend money on anything that I won't be able to use.
The author may suffer from a common problem among academics and other domain experts : knows the subject intimately, but is unable to adequately impart said knowledge. Reading the other reviews on this page makes me realize that different people view the same material in quite different ways. If only all the O'Reilly books were up to the standard of those written by people like Christiansen, Schwartz and Srinivasan ...