And their stability is questionable. While it's not that bad, I experienced their server crash more than once. Never had server crash on my own hosted ventrillo server, not once in a 5 years.
I use Discord every day. I would say that there are issues about once a week or few weeks where text messages are delayed by 10-30 seconds. Some of them don't arrive either. Using it for text communication at those times is challenging. I'm unsure what happens to voice chat at those times, but the text part is infuriating.