I was on Squabbles for a bit when the API changes were looming. It was fine, I ran into nice folks, but more than the performance or the community, I was concerned that a single centralized site, run by one dude, who seemed determined to set it up to quickly monetize, was not going to be sustainable.
I admit that federation was not why I came to Kbin, but if federated sites are where open-internet folks are sharing links and pics and discussing them, then that's where I was headed. I suppose the good thing is that anyone who is deeply invested in federation working exactly how it was originally envisioned can continue to pursue that goal with their own instances, up to the point where they consider defederation with the (relative) normies.