HN as an aggregator of geek news is exceptional. It's not the first of its kind - Slashdot was quite similar - but perhaps because it's associated with the SF Bay Area, it managed to stay relevant while Slashdot withered away.

HN as a commenting community is markedly more hit-and-miss. We often comment without reading the articles, we are sometimes gratuitously negative for the sake of negativity, and there isn't any other place where I've seen so many people being confidently wrong about my areas of expertise. I think we'd be better off if we were more willing to say "this is okay and I don't need to have a strong opinion about it" or "I'm probably not an expert on X, even though I happen to be good with programming".