I like it! Main issue for me is that there is not enough content on my hobbies, and “all” content is mostly filled with reddit-this and lemmy-that (or now threads) stuff, which is annoying because I don’t want to talk more about the platform than actually using it. But I hope this will change with some time.
I use only the browser, UX and UI is pretty straight forward, but subscribing to communities of other instances is really weird. I need to copy the “handle” (i.e. !lemmy_support@lemmy.ml), and add it manually to my instance domain (i.e. lemmy.world/c/lemmy_support@lemmy.ml), and then I subscribe to it. I don’t know if there are other ways (besides finding new communities via “all”).
I’m not into the technicals of lemmy or the fediverse, but I guess this is not easily solvable, as an instance doesn’t know that I am the user of another instance.
Thing is, if this takes off and websites adopt it, FF will be forced to integrate it aswell. I’d be fine with some websites not working in FF, but my mother will call me and say “the internet is broken”. I guess Mozilla doesn’t want and/or cannot afford that.