I cleared this stubborn exam today with 89%. Surprisingly, I thought I will perform badly on the Criteria API questions. They form almost 10% of the exam, I got them all. :-)
Locking, Caching, Transactions and ORM concepts are all part of the exam. I have to mention that the part of overidding metadata in almost in all of these topics. They like those type of questions. Overriding Embedded attributes, overriding TransactionAttributes in subclasses beans, overriding in Advance collection mapping (Maps and Element collections), overriding between entity annotations and orm.xml file etc :-)
The topic that I didn't do well is the Advanced collection mapping.. using Maps. I did lots of practice for this topic and EclipseLink has a defect on persisting attributes that are mapped as Maps.
Used Enthuware Exam and the Pro JPA 2 - Mastering the Java Persistence API Nov 2009... and lots of experience at work.
Next up is the 1Z0-895