A couple of days ago Oracle finally provided us with an on-premises download for Oracle 12.2 Database.
Go and download load it from here
Download the Database App Development VM with 12.2 (This is what I did)
Over the past couple of months I've been using the DBaaS of 12.2, trying out some of the new Advanced Analytics option new features, and other new features. Here are the links to the blog posts on these new 12.2 new features. There will be more coming over the next few months.
and slightly related is the new SQL Developer 4.2