Really the only thing I don't like about HN's UI is how the comment lines aren't formatted to a readable width -- they run about twice as wide as a standard book line and maybe 4/3 as long as a normal online article.

What's more, comments are really difficult to read on a mobile phone, which is surprising, given that they are basically just plain text which should have the virtue of being easily reworkable.

That said, HN rocks, so I can't complain too much.