"You can pull your data from ObjectDB easily as JPA entity objects and transfer them anywhere using Hibernate, EclipseLink, OpenJPA, etc. Which other Object Database offers such an easy migration?"
That's a little quote one of the people from ObjectDB posted at TSS the other day. Here's what they say about ObjectDB, which probably applies equally to all object oriented databases:
"ObjectDB is a powerful object oriented database management system (ODBMS). It is compact, reliable, easy to use and extremely fast. ObjectDB provides all the standard database management services (storage and retrieval, transactions, lock management, query processing, etc.) but in a way that makes development easier and applications faster."
I think the last line there is the key - it makes development easier and faster.
The nice thing about OODBs is that they remove the disconnect between objects and RDBMSs that ORMs try to solve. They're *substantially* easier to work with, and if you don't need a regular DB are a fantastic choice (at least I think they are). Unfortunately most of the work *I* do requires a standard DB.