We used Neo4j over a year ago, and it was pretty unstable when we used it. The database files were getting corrupted pretty frequently (a few times a week), so it just didn't work out for us. Ultimately it was for a small feature, so rather than continue to struggle with Neo4j we just reimplemented the feature using Sphinx. Like I said, that was a long time ago and Neo4j may have gotten a lot better since then.