Couchbase has released the developer preview of the Couchbase Query Workbench with the launch of Couchbase 4.0 GA, addressing customer requests for a graphical user interface (GUI) to create and run N1QL queries. The Query Workbench, which can be downloaded separately, offers features like a metadata explorer, N1QL editor, and flexible query results presentation, enhancing the traditional command-line tool by allowing easier editing, syntax coloring, and auto-completion. A notable feature is the describe command, which samples documents to provide a schema description, aiding in writing better queries and identifying data structure differences. The tool is accessible via a web browser, requires Couchbase 4.0 GA or later, and invites user feedback for further improvements.