Until you need it, anyway. If you just want to try it out, Distro by Endgadget is weekly tech journal you can subscribe to for free. That and Mac|Life (99¢ a month) are the only two Newstand subscriptions I have.
The only way I know of to read RSS Feeds native app wise is to use Google Reader via Safari. The mobile version of the site is bare bones, but usable. The Desktop version works, but you need to use the two finger scroll to access your RSS feed list, if you have more than a few, and you can't expand/collapse folders. Might be a few other non-working features. I have not explored it in detail.
I use the Reeder app, because I prefer their interface to the web site's.