Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Poor in explaining usefulness

I really doubt that Bob knows anything about XML. Bob does not explain how to construct XML document, nor how to put it into reality. Just like when you go to a Swapmeet, the man keep telling you this is a good stuff, but he just can not tell you why it's good. A lot of professors are just like that, they really know how to talk, but don't know how to explain. Don't buy this book, I am planning to return it to Amazon. The more you read this, the more you confused about XML ....