I've installed ORDS. It's got some installer wackiness -- modifies the .war as part of the install.

Otherwise, it's smooth enough and runs in Tomcat.

I haven't used the REST features so much; we just use for the APEX pl/sql bridge (ugh).

Yeh that's neat, but I feel like that is just going to cost me something to play. Also, there will be other databases tied into this project as well SQL Server, MySQL, and RethinkDB.