You can embed documents, but also connect them using Relationships like in the Relational world, but at the Graph Database speed!
OrientDB supports SQL with some extensions to manipulate trees and graphs. Your Relational DBMS skills are save!
Eventual Consistency is cool, but many times you need full ACID Transactions. In OrientDB ACID Transactions are distributed across servers.
Span your database across multiple servers. OrientDB supports Multi-Master Replication that is the state of the art on distributed systems. Nodes can be added without complex configurations. This is perfect in the Cloud.
OrientDB supports HTTP REST and JSON out of the box. Example:
OrientDB is used in production by big companies and startups like:
OrientDB is FREE for any purpose, but if you're looking for professional support go here.