Oracle previously released 12.2 as "cloud only" in a first-of-its-kind approach last year - to the frustration of many - but now it is available "on premises" as well. So that means anyone can download it from Technet and install on their own machines for testing purposes without having to get entangled in Oracle’s Cloud offering.
12.1's end of "Premier Support" is set for July 2018 with Extended Support until July 2021. So the clock is already ticking yet again in the unending march forward to maintain support on your critical database software.
At Solvaria, our Oracle practice has seen a steady uptick in 12.1 adoption after the longer-than-normal gap between 12.1 and the release of the .2 version that many DBAs typically wait for. We have found 12.1 to be very solid and have helped a number of customers with migration efforts pulling databases as far back as 10.2 to 12.1.
12.2 appears to have more than the normal amount of "release 2" features, such as Active DataGuard Farsync, Heat Map and Automatic Data Optimization, and enhanced analytical features. So stay tuned as we continue to explore it much further now that we can put hands on it!