I think it maps much better to document databases.

Nodes are just documents.

You just need to slap on a relations document type for the graph edges, and to store edge properties

I was close to finishing at least version 1.0 of a document/graph database on top of Cassandra and dynamodb.

With Neo4j properties and list members cannot be complex objects just like DB table rows. I was thinking that my dream DB would be a hybrid of MongoDB documents with Neo4j type relationships between them.