What reddit is good for
It's essentially usenet, except it's owned by a company who have ultimate control and there is advertising. So it's a way of spending an enormous amount of time arguing with idiots, there is porn and, inevitably, a very large number of people with really offensive attitudes (I'd be interested in knowing what reddit's demographic is, but I'd guess it's essentially 18-25 white US male). Unlike usenet most forums ('subreddits') are moderated and there is voting so spam is not such a problem (but don't say anything that might be unpopular, even if it is true). Like usenet it is slowly being overwhelmed by awfulness of various descriptions, but in this case, since it is owned by a company who can potentially be held liable, it will fall to bits in different ways.
I suspect it's on the way down now, but I would suspect that having fairly recently walked away from it after 8 years or so (the 20 years before that being wasted on usenet).
It's sad that there seems to be really no good way of actually finding what the news is in various specialised fields which is stable in the long term.