In short Hibernate Search by Example is a great how-to guide if you quickly want to get started with Hibernate Search.
Hibernate Search by Example is a thorough how-to guide to Hibernate Search. It shows and explains by clear examples how to setup and use Hibernate Search.
The book is clearly written and a pleasant read. It is not a long read but it still covers the basic and advanced features of Hibernate Search. It is not a full fledged reference guide but it gives you more than enough information to integrate Hibernate Search into your application(s).
The sample application which accompanies the book has an implementation using plain Hibernate as well as JPA. The plain hibernate sample comes with an annotation as well as an XML version. Basically there is a sample for each technology, which is a great plus for the book.
At last the book also shows some of the more advanced features of Hibernate Search and again shows more than enough code and information on how to implement and use these features.