Yesterday I passed exam with 93%. I prepared for last 4 months with 2 hours daily. Read the following books. EJB3 Orielly EJB3 in action EJB3 pro Specs Enthuware
Question from enthuware were of great help as they gives indication how questions would be in exams and to my surprise couple of question were almost same. I started using enthuware only 2 week before exam.
I like almost all the books. Initially started with EJB in action which is good specially for starting as it explains the things in simple way. Then I went to Oreily EJB3 and after that I read EJB Pro for JPA. EJB Pro was best of all for JPA as it explains the things more elaborately and gives examples with Servlet. In the end I read the specs for final touch to exams.