Start 11 1.0 is considered a full released product. But development will continue as Beta releases so if you update you will once again enter Beta for start 11. The change logs can be found in the start menu products sections pinned. With this release it is "start 11 1.01 report thread" change log is the very first post
I would rank this Beta as very stable. It may have been more of a test flyout since once the Taskbar changes enter Beta that will need more attention from Beta testers.