Oracle Database 12c Release 2 feature support includes but it not limited to: Analytic Views in the Connection navigator, Application Containers for the Multitenant Option in the DBA tree, longer identifiers for database objects, and SQL Developer is now using the 12.2 JDBC driver.
Oracle SQL Developer Command-Line (SQLcl) is a new, modern command-line interface to Oracle Database. It is available as a stand-alone download, and is also distributed with Oracle SQL Developer. The SQL*Plus, SQL, and PL/SQL engine is also shared with SQL Developer, so users can run the same scripts in SQLcl and SQL Developer. SQLcl commands like INFO[RMATION] are also available in SQL Developer via the Execute as Script (F5) button.
Oracle Real Time SQL Monitoring, a component of the Database Enterprise Edition Tuning Pack, is now available in SQL Developer using a new and improved interface. Users can watch queries run in real-time and observe progress in their execution plan steps as well as get key information in terms of resource usage and distribution of the workload in the parallel processes that may be spawned by their task.
The Instance Viewer, a new feature introduced in version 4.1 of SQL Developer, has been enhanced to include Top SQL report. The list is sorted initially by CPU, and automatically refreshes. You can drill down on an individual query to see it's plan, execution history, and create a SQL Tuning Advisor task.