About 10 days ago, Samsung had begun delivering the update packages to Android 8.0 Oreo for the Galaxy S8 and S8+ models, but it stopped within a few days.
Apparently, some models were unexpectedly restarting after the update to Android Oreo, so Samsung decided to halt the process until they find a solution to this bug.
After a week of waiting, Samsung has resumed the upgrade package delivery process, which also brings an improved interface, the Experience 9.0. The package is quite large, it’s about 530MB and should reach all users around the world. Unless there are other problems.
You can find in the source link all the improvements and changes brought by Android 8.0 Oreo and the new Experience 9.0 interface.