I'd say it's definitely a hybrid of the NoSQL movement and SQL. You have joins, data integrity (not giving a thumbs up "A+++++++ would write again" until data i

I'd say it's definitely a hybrid of the NoSQL movement and SQL. You have joins, data integrity (not giving a thumbs up "A+++++++ would write again" until data is on disk), and expressive queries. On the flip side, you have real document storage and querying abilities: you can query on subfields of subfields of etc. You can index arbitrary components of your documents. The best part is the auto-partitioning/replication. As someone who's used it for over 6 months now (4 in production) can't say I've regretted the decision or ever looked back. Every time I've hit a bug or a problem, the Rethink team has stepped in to make it right, even to the point of patching the database for me personally when things got rough (index corruption) and helped me recover all my data into a new instance. My advice: if you are happy with PostgreSQL, stay with it. It's not worth switching databases if you are happy just for the hell of it. But if you're looking to build a new app and need to scale the database to more than one master three slaves without the ops nightmares and you don't mind learning something new, definitely give Rethink a shot. The guys building it are really smart and the community around it is excellent (and growing steadily).