Smashing Magazine are known for informative articles on web design and, more recently, informative books too. Smashing UX Design is not the first of their books to cross my path and I've learnt that, much like O'Reilly books, they are about providing solid value ahead of pushing out book after book regardless of the quality of the content.
So with Smashing UX Design you have over 400 pages devoted to user-centric techniques for perfecting web site design. These guys are the experts and if you have the budget to do it properly this book gives you all the information you need to get it done - or enough to tell you that you should hire the authors in.
Alternatively if, like must of us, you don't have budget to blow, this book gives you enough information to work out what to prioritise and how to get the maximum benefit from your investment.
I've not read the entire book - yet - but I've read enough to know that it is going to be extremely useful over many projects to come.