I've started to look into RethinkDB in the past, and I'm very interested in the features it claims. However, I only have so much time to investigate new primary storage solutions, and our team has been burned in the past by jumping too quickly on a DB's bandwagon when the reliability, performance, or tooling just wasn't there.
As of late, we've come to rely on Aphyr's wonderful Call Me Maybe series[0] as a guide for which of a DB's claims are to be trusted and which aren't. But even when Aphyr hasn't tested a particular DB himself, some projects choose to use his tool Jepsen to verify their own claims. According to at least 1 RethinkDB issue on Github, RethinkDB still hasn't done that[1].
Not to poo poo on the hard work of the RethinkDB team, but for me, the TL;DR is NJ;DU (No Jepsen, Didn't Use)