I actually started on Kbin.social, but then it got shut down, Kbin died and now fedia.io seems to be the largest one running MBin. I like the interface on MBin and I guess it’s good to have a diverse fediverse with different services, but at the same time, why use mbin when everyone congregates on lemmy instances? The local magazines on fedia are for the most part, quite dead, when compared to lemmy collections. In the end I feel like there aren’t enough people to go around to support many more services like MBin and Piefed.
It’s mostly fully compatible to Lemmy. The only minor thing I noticed is that Lemmy edits are not getting federated properly (maybe that’s fixed by now, I just noticed it in some threads in the past).
Federation issues of course can occur, but that can also happen with Lemmy, or activitypub in general. I’ve been pretty happy with it as I prefer the UI just way more.