The SimpleRSS application is extreamly easy to use. It uses a simple blue sidebar on the left to navigate articles, and a small toolbar at the bottom.
With the comments button in the toolbar you can easily jump to that ardicles comments - even if it isn't on that page. If there isn't a comments section, SimpleRSS will try to find a forum page for that ardicle. It doesn't get any simpler than that.
SimpleRSS is also compleatly OS X Lion-ready with fullscreen mode, 64-bit, and everything you would expect from a moder Mac application.