I just tried Threads for about fifteen minutes. Currently, it's overwhelming and... not good.
Every single Threads user is displayed in your home feed, with zero option to only show content from people you're following. Hashtagging doesn't work yet, and most profile edits need to be done from your Instagram account, which clearly demonstrates that Threads isn't so much a Twitter/Mastodon/Bluesky competitor as much as it is an Instagram DLC.
I'm sure it's gonna do gangbusters since it's baked-in to the most popular social platform in the world, but... it sucks?