About the book, in my opinion investing in education is always good. And considering the fact that ideas that you might get from such a book could make you a lot more money that the cost of the book itself, I think it's worth it. I can't speak about the quality of the book though, I never read it.
About PS / Illustrator, I've used both to an advanced level, and I loved working with Illustrator when I was doing print work. But with web design I like to cut and paste mockups together, and PS is more flexible as a canvas so I prefer it for web design.
About PS / Illustrator, I've used both to an advanced level, and I loved working with Illustrator when I was doing print work. But with web design I like to cut and paste mockups together, and PS is more flexible as a canvas so I prefer it for web design.