Any book is better than reading disjointed blog posts and online pages. I learned CSS in 2006 from the then-new book, Web Design in a Nutshell, and after a month I was already way more comfortable writing CSS than three months of reading various blogposts.

You have to really, and I mean REALLY want it, because it’s £45, even on Kindle

It's literally the definitive guide on CSS, and frankly, it's the gold standard for any book calling itself a definitive guide. An inordinate amount of work went into the book's 1126 pages. You will learn something every time you open the book. It will pay for itself the next time you wonder, "how do I do X with css?", because you don't have to search. It's right there in the book.

If you do software as a profession, is the book really THAT expensive at £45? Having a deep understanding of CSS could make you significantly more than that.

I was about to argue that there can be no definitive guide on CSS as it's a technology without a single manufacturer and it has a 20 year old history. But then I saw the length of the book:

"Print length ‏:‎ 1126 pages"

Ok, I'd say it's legit.

Simplistic analysis of whether CSS sucks: this definitive guide is 1,126 pages long. On the Amazon page it also suggests the "Definitive guide to JavaScript" - it's 704 pages long.

If you can fully explain JS (an inexplicable bodge built on a tower of inexplicable bodges) in less pages then CSS almost definitely sucks.

It's a long book because of the copious visual examples.

I said it was simplistic :). Point taken.