I used it and understood how it works but I think it's trying to be too much at once and in turn failing at all of it. I'll try to break it down in case anyone else was confused:
Basically the idea of kbin is to join Twitter and Reddit but also make it federated. You have communities like in reddit (called magazines) where you can post threads/links like you'd expect. And then you have a microblogging section that's literally just for people to post like on Twitter, but that section is also federated with other Activity Pub software so you can see posts from people on mastodon and stuff (and they can see your posts too) and you can also follow these people to have your own social timeline. Oh and I forgot to mention but each magazine gets its own microblogging tab so there's no one unified one.
All in all, I understood it and I liked the UI quite a bit but it's just too much at once. I don't understand why you'd want to replace both Twitter and Reddit with just one site. When I go onto Lemmy I immediately get what it's trying to be and how it works. With kbin, even after I understood it I never "clicked" with it because I just couldn't wrap my head around having these 2 very different services in one. I much prefer having Lemmy for my reddit-like browsing and my misskey for my Twitter-like browsing.