I have seen a few CSS learning resources and they all take the same approach. Let's list out all the details of what every thing means and how CSS works.. Normally with a few examples but not really approaching the true complexities of real web sites (layouts and positioning can be tricky in particular ).
This book comes with example code that you can load up into you browser and using an extension such as Firebug, actually tweak the various settings in place and see what the results are. By combining this with the descriptions in the book for each pattern I have found I can actually understand what's going on ! This is a neat way to learn and sure beats trying to 'reverse engineer' random pages you find.
I'm amazed that the first chapter of this book doesn't direct the user to install Firebug in bold caps, and show a large screen shot..
Firebug is the best way I have found to make sense of these patterns with out hurting my head too much. Once you load up the examples and start playing you will finally feel like you are really getting some where with CSS !
The book does cover HTML5 and CSS3 but I don't think introducing these newer technologies is necessarily its main focus. So be warned.
If I was being very critical I would say the quality of the screen shots could use improving a bit. I find some of the patterns are explained a little too 'succinctly' and can therefore take some time to understand. Having said that, I would again reiterate that you /NEED/ to load the examples up. To be fair I would probably give a 4.5 if possible.
Note that I have not read the entire book, I have benefited from the chapters on positioning though and will update my review.