The release notes on the Catalyst 10.11 Radeon/FirePro graphics driver for Linux is not available at this time. However, if my memory serves me from the private test candidates, there really isn't any exciting or noteworthy changes to be found with the Catalyst 10.11 driver. Catalyst 10.10 was great as many found out early, but this month's update is likely not to get overly excited about. There is though likely some maturity to the Radeon HD 6000 series support and Fusion APU Linux support seeing as the open-source code has already been written.
Tell us about your Catalyst 10.11 Linux experience in our forums where it's sure to be discussed at length.