I'm quite interested in the upcoming official Java driver; I tried to use RethinkDB for Clojure, but by then the DB was several versions ahead of what the Clojure driver supported (the tests would randomly fail, in a different place each time they were run).

Eventually, I swapped my project over to Redis, which was reasonably well suited to the task (a scraper with independent values, the whole db is held in memory and shipped to the client and queried locally).

Still, RethinkDB would have been nice for future proofing, once it is time to implement user accounts etc, so I'd like to switch back in the future.