This article is consistent with my experience. One thing I'd add is lack of search. Many instances outright disable searching, and those that enable it have it

This article is consistent with my experience. One thing I'd add is lack of search. Many instances outright disable searching, and those that enable it have it painfully slow and/or unfederated. I see there is a /tags/<hashtag> URL now which is fast, so at least there's that, but a few years ago when I tried it, this didn't exist. And I don't see how you can access it from the UI anyway.