I've used it heaps, on various devices, you will need the UNA or Jitsi app to use it on mobile, but it is rock solid. Jitsi claim it can handle up to 70 people on a call, but I haven't tested that many, certainly stable for up to ten. We are currently deploying a client specific Jitsi webcasting solution based on Jibri that will handle a webcast to many thousands.