HN seems to have a different set of values. While there's less tolerance for jokes and culture references for the sake of culture references, HN tends to house a lot of intellectually frank discussion that a lot of other sites discourage.

A good example is this post from several weeks ago on the subject of denying blood donations from donors with a history of male-to-male sexual contact: http://news.ycombinator.com/item?id=3237895 It's very fact-centric, to the exclusion of any sort of pandering or apology. When I read this post several weeks ago, I immediately thought, "this would never fly on reddit; people would quickly downvote it for being 'insensitive' or similar."

This also reminded me of PG's essay "Persuade xor Discover." http://www.paulgraham.com/discover.html HN users seem to care less about "persuasion," which can lead to perceptions of "unfriendliness" because things aren't written to please people. However, it does lead to a lot of interesting discussion that couldn't take place on a site more concerned with being "nice."