Hacker News Reader

Is there an implicit understanding that these are all "good" discussions?

Not necessarily. Some of these might be universally hated.

I bet all of them are pretty interesting, however.

It is true that some of the discussions actually hated some books. So I tried to use the sentiment score to characterize discussions.

If you check the sentiment score of a discussion from my site, it shows you that whether the discussion is good or bad.