It is, but presumably you have seen a chat application before and thus already know where to type, and can deal with a totally standard website sign-up flow too. I don't like Discord, but it isn't difficult.
Midjourney users are sectioned off into separate rooms. For me, Discord ran into an updating bug and either they didn’t assign me to a room, or the app failed to surface the room. I had to force quit the app and restart it. I’m not familiar with Discord so I can’t comment if bugs like that are endemic or not but it doesn’t make a good first impression.