The multi-user aspect is super handy. It's also nifty that it exposes pretty much all of the functionality via a REST API, complete with the ability to manage

The multi-user aspect is super handy. It's also nifty that it exposes pretty much all of the functionality via a REST API, complete with the ability to manage OAuth clients/tokens. Not something I expected to really leverage, but have been surprised how frequently it's come in handy.