When I saw this book in my library search results, I couldn't hit "reserve" fast enough. I want more experience with all four languages in the title.
I'm not very far into this book yet. So far, I'm not enthusiastic. The book seems more interested in teaching us XML jargon than how to use XML. And it bandies the jargon around for several pages before giving a clear explanation of it. I've been writing HTML for ten years, and I was really baffled by the phrase "character entities", which the book threw around for several pages before it became clear that they were just talking about special characters like ampersands that can give you programming trouble. Grr.
I thought the age of the book might mean it would be easier, that everything in there would be extra-standard. But I think it means that standards, and even the language, hadn't quite been settled yet.
On a positive note, I like that at the end of Chapter 1, they tell you which chapters to focus on given your experience with XML and the other languages. I'm hoping there are more examples in the PHP chapters and less (outdated?) jargon.