The beta release notes are available in the Software Update window and also in the Version History section of the manual (in the Help menu).
This thread will be updated with information about compatibility with macOS 10.12 Sierra as it becomes available.
We do not recommend using a macOS beta on your main Mac, as there may be bugs that we have not had time to, or cannot, work around. With that said, we do welcome bug reports so that we can investigate any bugs and report them to Apple or try to develop workarounds. Please submit any feedback or bug reports via e-mail, rather than posting here.