Diving into the book itself, Jason covers 16 Design Patterns. He covers the basic ones like the dreaded and horribly abused and misused Singleton to the more advanced Active Record and Table Data Gateway. While he covers all of them to a good depth, there are a number that deserve special mention.

These "mentionables" include the Strategy, Observer and Mock Object patterns - all three Jason covers well with some good examples included. Overall, he found the book good, but needing some work in some areas (like in updated code samples).