At least on the iPhone, I use an app (http://itunes.apple.com/us/app/news-yc/id434787119?mt=8). You can find hackernews apps on iPad too, but browser works fine for me.
(edit: Tried it out, and it still isn't as usable as the website. It still has larger fonts and only shows three short lines from each comment at a time. The list of articles also has variable sized rows that often overflow onto multiple lines with other text at the same level: difficult to skim the titles quickly. I'd much prefer a subtle change to the mobile HN website to fix the buttons ;P.)