This is an excellent and exciting step in the right direction, for a major business to establish within its corporate governance a regularly scheduled public report on an area of public accountability interest. For Dropbox, that issue is of course data privacy/security. The report itself has lots of folks on my Twitterstream up in arms with fury, over its released statistics. It's also generating some media buzz along the same lines. But, guess what? We're not guessing. We know the real numbers. That's a big risk for Dropbox to be taking. We need to support and applaud that effort.
The commitment to hold itself accountable to its customers—regardless of probable press responses and/or customer retaliation—is un-orthodox, carries with it a lot of risk for Dropbox, but is also a risk the Tech community is ready for. Parallel to their Transparency Report, Dropbox also has posted a plain-English, short-read page that outlines its Government Data Request Principles. Upon doing further research, I also uncovered their Privacy Policy and was very surprised to find it formatted... not in all-caps, not packed with legalese, and not a gazillion pages long. Its sections are broken-up into tabs, and it's—like—usable! What can I say: warm fuzzies abound for this UX'er, upon seeing just that.