I somehow managed to convince 4 of my friends to use Riot and it's been great. We were originally using Group Me.
My friends are not tech savvy and couldn't care less about software freedom or privacy, but I was able to convince them to switch by luring them with the fact that they could post unlimited size videos. It's actually the easiest way to share high quality videos between Android and iOS users.
The only thing that annoys me is when you release updates to the default configuration file and I have to manually resolve the differences in the middle of an APT upgrade. That's not a big deal though.