But of course with reddit, it's 100% up to you to make it good. Find the right communities, ditch the wrong ones, and you're going to have a great time.
"All over," no--it's mostly, though not always, contained to the topics at hand. Most times that Sheryl Sandberg or Ellen Pao or any group that would maybe like to encourage people who are not dudes to learn to code and maybe get a job come up, this has historically bubbled up. Similarly, topics that do not revolve around white (and occasionally South and/or East Asian) men usually come with a sidebar of pseudoscience-cloaked racism or the blurfing of "equality of opportunity" with its implications of inferiority.
It has certainly improved since 'dang and 'sctb took the reins. And you can't be an overt meme-turd here and get away with it. But adjusting one's pince-nez and well-actuallying into sexism and racism isn't really better, and on that HN has a ways to go.