I got this book thinking, "Hey, this might help me get a leg up on that new PHP 5 OOP stuff." That it did.
However, this book accomplishes much more than that. Zandstra sets himself a several goals and meets them all quite well. These include: providing an understanding of classes, objects, and interfaces in PHP 5; presenting a numbers of useful design patterns as expressed in PHP 5 terms; giving the reader information about and insight into advanced development tools and methodologies for large-scale PHP 5 projects.
If this were all that the book covered, it would be useful in and of itself for this alone. But the author also gives us a good, thorough grounding in both the mechanics of PHP 5's new object model and (especially important!) the rationale behind it. He also provides a nice tutorial on UML modeling along the way, and finishes up with a look at some current development tools like Phing and CVS. There are plenty of helpful and useful examples along the way.
I give this book 5 stars for having really helped me wrap my head round some advanced OO programming and design concepts. I've already got loads of use from it; my copy is about two months old, and it's already getting dog-eared. It's also a very enjoyable read, and a real cut above most of the "How To Program In ..." sorts of books. This is the perfect book for someone with some experience with writing PHP code who's looking to move up to the next level - creating real, scalable, enterprise-level PHP applications.