Oracle's own OTN JDeveloper Forum provides a good place to drop technical questions about the whole JDeveloper suite. Yet there is another less known avenue better suited to overview questions.
ODTUG maintains a number of mailing lists including the JDeveloper/Java specific ODTUG-JAVA-L list. This list among 13 odd others (including Apex) is open to the public. (If this link doesn't work, access the homepage and click on "Join an email list").
This list unlike OTN's forums is mostly silent, but on occasion explodes into activity. It is actively monitored by Oracle's JDeveloper Product Managers, and other known Oracle-JEE names such as Paul Dorsey and John Flack.
Questions tend to be less technical in nature and more of an overview which elicit many good and detailed points of view. For instance there is a current discussion on "Oracle Forms and PLSQL conversion tools [to JDeveloper]". Unfortunately if you're not a member of the list, there's no way that I know of to read those posts (can somebody correct me on this? .... is there a public and up to date aggregator?).
After you join this list you may not get any posts for sometime, but when you do, they're well worth the read. Thanks to ODTUG for making these lists public.