The update is beta version 25 for the OnePlus 3 and beta version 16 for the OnePlus 3T. Apart from upgrading the OS to 8.0, it also brings September’s security patch.
The change-log mentions that users will get features such as picture-in-picture mode, autofill, smart text selection, and notification dots. In addition to those is a redesigned quick settings and the ability to upload photos directly to Shot on OnePlus.
Some known issues listed are a slower fingerprint sensor, no shortcut access to Google Photos, and stability issues with NFC and Bluetooth.