The current about page (http://duckduckgo.com/about.html) is dedicated to answering that question. Are you saying you think I should add a summary sentence on the homepage? I just haven't because I don't want to introduce clutter.
I think it’s acceptable as-is, but I can’t help but notice that Ixquick (https://ixquick.com/) very directly markets what differentiates itself from other search engines (re: privacy).
Summary sentence wouldn’t be bad, a la Google’s homepage.
