I have a bit of a discussion on which are
the best books for learning Hibernate. In summary:
You really need
Data Persistence with Hibernate by Bauer and King. It's the standard, and covers EVERYTHING at an advanced level, but in covering everything, the readability is understandably sacrificed. So, I always recommend a second or third book for actually learning Hibernate.
I wrote a book just on this topic, and it's called
Hibernate Made Easy. Of course, I think the book is great, and I get great feedback, but then again, I am a little biased.
I also really recommend Harnessing Hibernate. It's well written and doesn't try to boil the ocean like Java Persistence with Hibernate. It's also a very recommended intermediate book on Hibernate that makes learning a bit easier.
I think those three books are really a great hat trick of learning!
My Book Recommendations for Learning Hibernate Quickly -Cameron McKenzie