Update - Dec 13th 2018: Oxygen 2.1.2 is now available, which includes a fix for compatibility with the just-released WordPress 5.0.1 update. Everything written below also applies to Oxygen 2.1.2.
Oxygen 2.1.1, which includes fixes for compatibility with WordPress 5.0 and the latest update to Toolset, is now available.
If you are not running WordPress 5.0 or the latest version of Toolset, there is no reason to update to Oxygen 2.1.1.
It is purely a maintenance release.
Can I use Oxygen with the new WordPress editor, aka Gutenberg?
Yes, you can use the new WordPress editor (known as Gutenberg during development) with Oxygen:
Can I use Oxygen 2.1.1 with the Classic Editor on WordPress 5?
Yes, it works with the Classic Editor too.
Can I use Oxygen 2.1.1 with WordPress 4.9.x?
Yes, Oxygen will continue to work with WordPress 4.9.x.