For the content to be consumed over the web RSS has particularly given a new approach. In order to distribute content to the reader almost every website use RSS feed. In order to see the RSS reader Google reader is the best RSS reader in the world. The only problem of it is being a web based Application. If all of are connected 24/7 to the internet than it is no more a problem. The offline mode is not offered by the Google Reader.
Desktop application provides more features and the applications that are run through a browser usually do not provide that much features. Integration with OS interface is generally better in desktop applications.
You can read your RSS feeds offline with the help of Gruml which is a Desktop based Google reader client. For the users Gruml provides Mail.app type interface. You can see the folders and the feeds on the left, the post heading on the top pane and the text at the bottom.