Quite some books were written about mod_perl 1.3. The best one - in my opinion - being the mod_perl developers cookbook, by Geoffrey Young and Paul Lindner. Compared to that book, this one doesn't read like a Michael Crichton novel. It's not written as well and it doesn't give you the same level of apprehension. It has the structure of a guide, but more and more it reads like a reference. But as a reference it's not as complete as you would expect. It's not as complete as Stas Bekmans earlier book Practical mod_perl. In the mod_perl 2 User's Guide, for example, you will find how to retrieve the value of perlSetVar, but not how to set it and certainly not how to figure that out yourself.
But, it is the only mod_perl 2 book that's on the market right now. And it's great that there finally is a mod_perl 2 book. So I don't regret buying this book. If you're into mod_perl, you have to buy it.