As you can see from the screengrab of the installer, this is not a stable release. And it crashed on me a few times as I tried out some of the new features, including the new on-canvas text editor. But here are a few of the changes in GIMP 2.7:

• GIMP resources such as brushes and patterns are now taggable.
• Save as and Export functions have been separated. To save a file as anything other than an XCF file, you need to use Export.
• Enhanced size entry widget
• Refinements to the layer mode menus
• Status bar feedback for keyboard changes to brush patternsTEST

You can read more details in the release notes or changelog