If you still use the original version of Google Reader, you'll see this warning:
"We'd like to let you know that very soon we will be retiring our old Google Reader interface. Although we're sad to see it go, we're happy to report that we've been working hard on making the new interface as slick as possible based on feedback from users like you."
The initial design, launched in 2005, wasn't very successful and Google had to change it one year later. In less than a year, Google Reader became one of the most popular web-based feed readers.
Google Reader's initial interface was based on Dave Winer's idea of "river of news": the most recent posts are placed at the top, without any categorization. "Instead of having to hunt for new stories by clicking on the titles of feeds, you just view the page of new stuff and scroll through it. It's like sitting on the bank of a river, watching the boats go by."
The old Google Reader placed all the posts in the left sidebar and you could move to the next post by just hitting the space key. You could get a similar experience in the new version by changing the start page to "All items" in the settings and selecting the expanded view.
But people from Google Reader's discussion board disagree:
"For someone wanting to be able to quickly skim through all of their news feeds (like me) the old interface is simple and elegant without the unnecessary clutter that the new interface has," says Michael.
Google Reader has recently graduated from Google Labs (even if the logo doesn't yet reflect that), has a new Google Group and prepares the launch of some of the most requested features. Matt Cutts told Information Week that "Google Reader search is one of the top priorities on the team's list".