Yep - it would also be great if HN provided an indicator of which way you voted. As it stands, I'd say I probably get it right about 75% of the time, but who knows? It's impossible to tell if you've upvoted or downvoted a comment still; and especially on mobile, I bet I get it wrong pretty often.

It has been suggested many time before to move the up and down arrows apart on mobile - something like

^ —- greatposter —- v

The one good that come from the current system is it helps you avoid taking a down vote personally since it could always be a fat-fingered up vote.

How long do you have to be on the site or how much karma do you need in order to downvote?

About 500 karma to be able to downvote comment, I believe (you can't down vote submission).

You're on iPhone aren't you. Having used both iPhone and Android for some time now I think its crazy how much more accurate Android is with pointing at small links on-screen. And in the rare instance it's not confident about what you meant to push, it will zoom in a bubble and ask you to click again (confirm), where the iPhone will just not do anything.

Yes an iPhone - it is so easy to down vote someone by accident that I tend not to vote when on the iPhone.