I used build 10512 on my 640XL for 2 days. It went fine.
1. Pictures can now be saved when editing on rich capture.
2. Transferred a pdf to my phone via bluetooth but the toast notification freezes and isn't clickable. File doesn't show anywhere inside the system.
3. Time and quick status has a 2-4 second delay when waking the phone.
4. 1975 wallpapers didn't show up in my phone.
5. Blinking quiet hours(like the others)
So i did a hard reset to "fix" some problems, but the they were still there. Worst is that my phone "didn't succesfully restore backup" and somehow i started from scratch. Hard reset again but still the same problems and error in backup.
I use my camera most of the time and the deal breaker for me is that i can't edit pics on Fhotoroom anymore: When launching/picking pics on the photo app, it crashes. So i rolled back to 8.1. Small reason tho, but i still want to update again to 10512.