I'm half-way through this book and as other commentators have said it is not a very well organized book but the information is there. The author makes a token effort to explain some details and then trails off with "we will come back to this later". My advice to the author would be: Explain it fully, or don't bother mentioning it.
I also think that it would have been less confusing had the author chosen to use Hibernate annotations throughout the book and perhaps dedicated two or three chapters at the end to showing JPA annotations, XML mapping and XDoclets instead of repeating various examples with the different methods.
If you want a book that will give you enough of the basics in early chapters to use Hibernate effectively then this is not the book for you. However, you will learn from reading the book and the copy I received came with a coupon code to get the digital version for free, which was an unexpected but nice touch. Once I have read it fully, I expect it to serve as a nice reference.