Is the NSA PRISM leak much less than it seems?

So, if PRISM doesn’t give the NSA unfettered access to all our online files, Gmail messages, Facebook posts, and tracking metadata, what does it do?

Basically, “PRISM is a kick-ass GUI [graphical user interface] that allows an analyst to look at, collate, monitor, and cross-check different data types provided to the NSA from internet companies located inside the United States,” says Marc Ambinder at The Week. That data is stored on U.S. servers, but “a lot of foreign intelligence runs through American companies and American servers.”