Although this could be seen as a minor release, it comes with lots of new features in ADF Business Components, mainly in REST support, and Data Visualization Tools among others, as well as a lot of bug fixes.
There are many new enhancements to Gauge components, we can now set a title, border and also set the indicator wider that the plot area.
There are some new components, the picto chart.
And the tag cloud. This is a component I have been expecting long time ago as we were able to use it as you can check in this link (Marrying the Worlds of ADF and HTML 5) but it was not available out of the box.
In ADF Faces there are two more cool enhancements as we can set an af:table to cache fetched rows so there is no need to re-fetch when the user scrolls back, and af:inputDate opens directly on the client instead of going back to the server.
There are more changes and improvements in ADF BC as REST Services, Groovy support and desktop integration.
You can check the complete list of new features and bug fixed in this link: Oracle JDeveloper and Oracle ADF 12c (188.8.131.52.0): New Features