On the whole, this is a well-researched and well-written book, although the chapters on XPointer could do with more concrete examples of how XPointer could be used, and also more clarity in places. The chapters on XPath are good, but are marred by two things. Firstly, the level of uncertainty about the details of the impending XPath 2.0 specification. And secondly, the function reference is not as good as it could be. The material on nodes, node-sets, location steps, paths and axes is excellent. However, before buying this book, you would be advised to check that the information you need is not covered elsewhere. For example, if you're interested in XSLT, then the level of XPAth detail in 'XSLT' by Doug Tidwell is probably enough. Oddly, the function reference in Tidwell's book is superior to Simpson's.