My favorite improvement is how it’s smart enough to return to your list of feeds after you mark the last item in a feed or folder as read (I’m a fan of anything that saves a click, especially on a mobile device). And I love how articles I clip on the iPhone reader automatically show up in FeedDemon’s synched clippings.
If you’re looking for a great RSS reader for your iPhone (or any mobile device, for that matter), give it a try at http://m.newsgator.com/