A total of 337 issues involving many components has been resolved, so it may take a while to download. A complete list is available in the release notes. In particular several software framework related bugs have been fixed.
Currently only the repository is available. This means that you can upgrade from 2.1.x. Go to Help > Software Updates... Add a new site "http://www.atmel.no/avr32/avr32s...". Select the Installed Software page, right click on "AVR32 Studio" and select Update... This will download and install the changed components.
Complete packages, including an installer for Windows will be made available on http://www.atmel.com shortly.