One of the premier RSS reader apps for the iPhone and iPad is Reeder. It syncs fast, it has a great interface, and it uses Google Reader as a backend (which means you can keep it synchronized with all of your devices).
The much-anticipated Mac version of Reeder is now available in public beta. While some of its features are still being implemented, you can get a good look at what the final application will be like.
The interface looks amazing. I think some of the keyboard shortcuts could use some work, but overall its very usable. I like the narrow column of icons representing the individual feeds. One minor change that would be welcome would be for them to automatically sort by the number of unread items, which I have found makes going through large numbers of items easier in other readers.
If you don’t like the icon view, you can drag the column to widen it and turn it into a text-based list instead.
The icons floating along the right side of the top bar can be customized as well. You can add your frequently-used “services” to it, allowing you to easily copy the item’s permalink, tweet the article, save to Delicious or Instapaper, etc..
One impressively styled, but infrequently used, element is the screen used to connect to your Google Reader account.
Reeder for Mac looks like a very promising application, and I cannot wait to see the final version. I currently use Reeder on my iPod and NewsFire on my laptop, which lessens the newsreading experience on both. Not having feeds and read items synchronize is a bit inconvenient. Reeder should solve that. NewsFire is a great RSS aggregator, but it lacks syncing.