Where previously there was only relational databases, the data store world is now rife with options like Key-Value, Document, and Graph datastores. Unfortunately, every datastore likes to show how it can be used for anything, but none of them really help people figure out when to use one model over another.
So, the question is: What "things" are graph datastores better at than relational datastores? (ie. faster, simpler, more flexible, more powerful) What makes them better at doing those things?