I liked Neo4j quite a bit, it could handle all the sensor/IoT data we could throw at it. Back then it had (and I'm sure still does) a beautiful interactive data visualization dashboard, great Cypher tutorials, and more.
Neo4j is a good database. I went to write a database driver for it, and found it extraordinarily difficult. I knew it would take at least a month of work to build.
At the same time really cool tools like Firebase were becoming popular, and Multi-Master database architecture with Cassandra and Riak were showcasing what high availability could do.
So I decided, rather than implementing the Neo4j driver, which I knew was bound to Neo4j's Master-Slave architecture, I would rather switch to Firebase or build my own mashup of all the tools I wanted:
- Firebase (realtime)
- Neo4j (graphs)
- Cassandra (multi-master / P2P)
- CouchDB (offline-first)
I spent a few weeks building a prototype and submitted it to HackerNews in early 2014. It was a huge success.
Since then, we've gotten 7.5K+ stars (https://github.com/amark/gun), raised venture capital money, and introduced decentralized cryptographically secure user blockchains, and a ton more.
Graph databases, to me, are so compelling, I have not only "used them again" but spent the last 3.5+ years of my life dedicated to building, improving, and making them more awesome.
I certainly hope others try them, even if it isn't GUN. They're worth a shot, but aren't a silver bullet, so use them where it makes sense.