I discovered Hacker News about 3 years ago and while at first I though "what a crappy old looking site with a bunch really technical articles". I would visit every now and again but recently, I've started to visit every day to the point where it's the first site I'll check in the morning.
But that's not what I love most about it. What I love most is the community of fellow minded people that are there. The pureness doesn't just come from the sites design but with how everyone interacts. From interesting articles to thought provoking discussions in the comments, you get a sense very quickly that on HN there is no agenda.
Also I have yet to see a place other than Twitter maybe where an article about a company is posted and the CEO chimes in the comments and discusses the article with readers. This all seems very natural on HN unlike other places because when you look at that CEO's profile, you find that they are a daily HN user. Less of "they are talking about my company, better handle the PR" and more of "oh look someone posted about us, lets see if I can clarify anything".
Overall HN just seems like a very honest place. If you haven't visited Hacker News yet I highly recommend it.