Adobe and Microsoft have worked together to test Creative Cloud and Creative Suite 6 applications for reliability, performance, and user experience when installed on Intel-based systems running Microsoft® Windows® 8.1. There are currently no known issues. Adobe Photoshop® CS5, CS4, and CS3 were also tested with Windows 8.1 and there are currently no known major issues.
As with any new release of an operating system, there could be unexpected issues that arise that were not discovered during testing. If you encounter any issues, report them using the bug reporting form.