Of course, they were kind of obvious additions and Twitter does them too now. Status.net also had a very handy, very slick XMPP interface, perfect for those of us who don't like to play "where's the setting" on a website. Unfortunately that got taken down with the upgrade to Status.net 1.0, and hasn't yet returned.
I personally run https://freesocial.org/ which is based on the StatusNet software.
Third-party clients have, however, not implemented StatusNet support despite the fact SN has a Twitter-compatible API. _That_ is something I don't understand why.
The activity can be small status messages like Twitter - but can also be anything else, like photos, check-ins, whatever. So in that way it's much more like a distributed Facebook than a distributed Twitter - but right now the existing clients out there don't really show that very clearly.
Let's not forget that Twitter would have never been that successful without its developer community. If you can attract developers to rstat.us, then you will probably attract more users over time.
Disclaimer: I have no idea if this can be implemented.