Status Updates From Design Patterns Explained: ...

Singletons are a terrible idea. Don't use them. They make your code harder to test, and don't solve life time issues. Create the objects you need and pass them down to where they are needed.

The analysis matrix looks like a good tool for software design

Yuck, the author is promoting Singletons again

"However, these topics are beyond the scope of this book. See Chapter 25 for more information on these areas."

Good chapter here putting together the theory and philosophy of earlier chapters.

Yet another mention of the dangerous Singleton pattern. In this particular case a reference counted shared pointer would be much better. I can only presume this 2007 book predated robust and wide implementation in the standard library.

The chapter on the Strategy Pattern is great for breaking apart giant class inheritance trees into separate class trees for each business rule or algorithm.

I haven't seen Expert Systems talked about for a long time. All about machine learning and AI now.