I've had nothing but positive experience with RethinkDB drivers. RavenDB has good drivers for some languages, but admittedly not every language is well-supported.
Still, I can't see a situation where I would choose a non-working datastore over a working datastore.
I'm having an excellent experience coding against RethinkDB in Tornado Python. A shift in programming style from conventional callbacks to use Tornado's gen.coroutine is necessary. Having made that shift it's become very easy to use coroutines in the server to stream RethinkDB's JSON result sets up to an AngularJS front end. End to end JSON makes for zero impedance and rapid development. I'm constantly rejigging my schema, indexes and joins as I go so it feels like RDBMS based dev in a lot of ways.
Still, I can't see a situation where I would choose a non-working datastore over a working datastore.