There is quite a bit of documentation available from Google on the benefits and uses of Google Analytics, but some of us are more visual learners. The following video produced by Google should be a good introduction for those users first trying it out.
Youtube - Google Analytics Interface Tutorial
http://www.youtube.com/watch?v=rHeKRvo6OhIQUOTE
A brief overview of how to use the Google Analytics interface. If you are new to Google Analytics or you'd like to pick up a few tips on how to use some of the different features, this video is a good place to start.