I checked the origin of the project and it seems to be an European grant to a few universities working on Semantic Web. Given the track record of this technology I’ll pass my turn. Neither the home page nor the doc provide any compelling arguments or killer feature for it’s use over existing solutions.

I’m not convinced either that a strong schema is really important for a graph database. In fact, even in OOP long chain of inheritance have proven bad practice. I also found myself that working with flat-type (no inheritance) nodes and edges simplify the code a lot.

Is this database used on any deployed project?