I pretty much just use it because my friends use it. Voice chat, screen sharing, and text chat are all generally really good (though I'm not a member of any massive servers which I imagine would make the text chat a lot worse). If my friends swapped to something else, I'd go with them and never use Discord again.

It looks okay, but the actual UX isn't very good. Simple things like DMing a friend, or making/accepting a friend request are way more arcane than they should be.

I guess I can't really blame Discord itself, but I hate that it killed forums. Its lack of searchability makes it almost completely useless at doing what forums used to do, but almost everybody migrated anyway.