It's a pretty popular. Have been using it for several years, using it for chatting and just playing games with my friends in free time. It's pretty enjoyable to use it as long as you have server to hop in.

As for cryptocurrency aspect. Most of the bounty campaigns are using Discord as their promotion media to gather communities for some quick updates which is pretty good in my opinion, people should use it to promote something that is "worth to promote" in this platform. But be aware that Discord is swarmed by those filthy scammers out there and some of the Discord users are pretty unaware of it.