I'm a user experience and interaction design professional, so here's my take from a slightly more informed perspective. As of 2009, this book is frequently recommended for UX practitioners through the UX Book Club movement.
What's good about the book is that it's shiny. It's stirring and inspiring, and offers a lot of wisdom along the way about the nature of the best design processes and the importance of lightweight sketching and trying, trying, trying. It will make you feel very good about design, whether you do it or know people who do, and I think that's why it's caught on so much with the UX Book Club.
On the other hand, many UX people want their books to provide useful frameworks or other practitioner-focused guidelines. This one doesn't, really. This is not a problem if you're looking for a more theoretical treatment of design. Of course, most practitioners aren't--many of them, underscoring one of Buxton's main points, sneer at "theory" in an excellent demonstration of what's wrong with designers. The problem is when a book suggests it's one thing but is actually another. Of course, a "theory" book would sell about as well as cold dog poop, so...
It's got a stunning design-related bibliography for the serious practitioner or researcher, and good tips for people starting out. It may well remind you of the right answer as you read. It's not going to make you a designer; arguably, it may not even make you a better designer in most situations. I can think of about a dozen UX books you should buy before you get this one. It's worth reading, but I don't know about a purchase. To paraphrase the author...it's designed right, but I don't know if it's the right design, or if it presents itself accurately as what it really is.