Using neo4j is pretty easy - you got nodes and properties and those nodes have relations. Doing a Mapping to pojos can be done quickly too - using spring-data-neo4j. And starting a new project is as easy as it goes with maven.

The neo4j Console is just plain cool. You go through your db like a folder structure, call cypher queries and simply adapt properties BUTit only runs in standalone mode with jetty. But you can quickly use it in any other project with a servlet and a few lines of javascript code.