Hi, I've been using JPA for some time now and been in projects where we've used both Hibernate Annotations and Toplink Essentials.
AFAIK the project leader chose Toplink because Netbeans had it integrated and seemed to be the easy thing to do.
However when looking for help, most of the literature seemed to assume that you are using Hibernate as the JPA provider, so, the question is, is have you found any advantage, performance or otherwise for not using the de-facto standard for JPA, Hibernate?