One facility that seems to be missing is the ability to search for groups on a particular topic or interest. I note the latest release mentions hashtags, but I do not see where a search for them is implemented or where the hashtags are added.
I have discovered that one may enter a hashtag on a post. When it is published, one may then click that hashtag to find other posts with that hashtag.
I think that some of the purpose of a hashtag is removed if one cannot search for different hashtags! This is why some people provide a Tag Cloud or enable the entry of a hashtag from simple input.
I also note that one is presented with an unhelpful blank page when one enters domain/hashtag/searchtag