This is the first update after the One UI was seeded to Samsung Gear S3 watches and while most of it is smooth sailing, there's one particular flaw that came with the new UI and that's alarm syncing. A new, rather small update, is here to fix that.
Before the new update, the watch used to sync the alarm with the paired phone and overrides your settings whereas now, your Gear S3 will remember your preferences and won't sync by default. The changelog also says there is some improvement to the overall system stability without going into specifics.
As of now, Gear S3 owners of the Frontier and Classic versions from Germany, Israel and Canada are receiving the OTA update but it will eventually hit other markets as well. We also suspect that Gear Sport will be getting it pretty soon.