After a long gap, there was an opportunity to jump into core JEE last week for a client. Though lots have been written about this here’re are some observations about it.
1) To begin with, after working with Groovy and Grails playing with JEE6 gave a stone-age feel 
2) Servlets with annotations is an absolute breeze now. No more web.xml configuration required.
3) The tag libraries .tag files for creating custom composite components is a welcome feature in JSP.
4) The dependency injection feature using @Resource, @EJB, @PersistenceUnit annotations save lot of code. It will remind you of Spring framework though.
5) Not many changes in the way EJBs are created using annotations and it was still making developers scratch their head, however.
5) JMS still has the same old boring piece of code to produce and consume messages. Create connection factory, connection, session, publisher, message objects etc. a long list of tasks.
6) Creating SOAP-based web services is incredibly easy, however the RESTful approach still needs some plumbing work.
7) Eclipse Indigo and Juno(the latest version) have reduced the effort of working with JEE6 tremendously.
8 ) The JPA implementation of Eclipse, EclipseLink helps you get started working with ORM asap, as you don’t have to configure framework like Hibernate for playing with the API.
9) JBoss AS7 has undergone a complete revamp. In fact, the modular(modules) structure, took lots of time to get a hang of it.
10) JBoss Tools plugin for Eclipse made us craving for more RAM and processor speed.
11) All of us started feeling the need for Spring framework halfway through using any API.
On a personal note, I missed Groovy a lot, because had to write so many lines of code to even implement a simple piece of functionality like inserting a record in the database.