Negative and contrarian is the internet message board default. It still happens all the time on HN, but in my opinion there is often a prevailing attitude of constructiveness that other internet communities can't consistently emulate as well.
I have to say I adore the community here. Even though sometimes comment threads dive into slashdot level examinations of detail and occasional political mess at times, the discussions are typically quite enlightened and remind me a lot of early Internet communities. It's typically harder to find that community online due to the popularism that typically dominates mature online communities.