For my job, I've been doing a lot of work on automated reports lately. The logic of the reports is written in Perl and the generated content is HTML. I've used CSS on some projects before, but decided to buy Meyer's book to learn some more of the details. I've been using the book as a general instruction guidebook and also as a reference while working on the automated reporting project.
Foremost, I am really impressed with CSS and the people who designed it. I haven't found a technology as useful as this in quite some time. When learning about a new technology, I evaluate it by roughly tracking how frequently it inspires me with new ideas. For this book, I'd say that rate was about one new idea every 15 to 20 pages. At 430 pages, that means about 20 new ideas.
Meyer's writing style was clear and concise. I wish he had found a synonym for affect, but that's a minor annoyance. He used frequent diagrams to illustrate the details of CSS in particular situations. He provided a good mix of prose, code and illustrations. I was particularly pleased with the chapter on CSS for non-screen media. Since management will eventually print my reports, that chapter was particularly valuable.
The book provided a good background and taught me many aspects of CSS that I hadn't originally noticed. Some portions of the book were a little too detailed. If I wanted to be reading the CSS spec, I would go and read the spec. Which brings me to the best CSS resource I've found on the web (now that I have enough background to understand it better): the CSS3 Selectors specification.