I agree it's a great book to have, but it actually explains a lot less than the articles I listed above or the talk I gave at YAPC::NA this year. In particular, it does not sufficiently address some of the shortcomings and pitfalls of inside-out objects. It's certainly not where I would suggest anyone go to learn about inside-out objects, though it has increased awareness and sent people to places like Perl Monks in search of details.