A preview video showing the Ruins of Sescheron, the new area coming with Diablo 3 patch 2.3.0, has been released.
The patch also contains the new Kanai’s Cube artifact, crafting system and adventure mode updates, the Season Journey interface, a new difficulty level, and some new legendary and set items.
In other words: lots of new, free stuff.
More background information on the Ruins of Sescheron area can be found over on Battle.net.
Diablo 3 patch 2.3.0 is currently available on the public test realm.