The strenghth of Google Analytics is the time factor. They keep all data of all you websites for a long periode and you can compare the statistics of the diverse websites you have under you control. An example is the situation in Japan. After the disaster of the Nuclear Plant and the Earthquake I investigated how many visitors from Japan there were just before and after the happening. You discover how visitors from a certain area aren't there anymore.
Internet seems so abstract sometimes, but with these tools you can actually measure the social impact on Websites when disasters happen.