To me also beta 6 does not feel like GM. Especially the annoying calendar / contacts bug when birthdays show with a day +/- 1 is not acceptable in my opinion for a release. But overall system runs quite smoothly. I also noted a bug in task manager. When closing apps by swiping always 2 at once to the top after 1 or 2 times you do that system no longer shows one thumbnail. Hard to describe, i'll give screenshots later when back to my pc.
Beta 6 is not supposed to be the GM..it's a hotfix that had to be released before the full newest beta was meant to be released next week (which would've been beta 6.) Now, the beta next week will be beta 7, followed 3 weeks later by the GM on September 10th.
(Supposedly.)