I had this installed in a bunch of my old Firefox profiles so I eventually checked it out before removing it.

It's probably an interesting extension for the privacy-illiterates who can't be bothered to install more than one privacy-related extension and couldn't care less about what happens under the hood. But its incredibly minimalist interface makes it very hard to understand what it really does, so I feel much better protected using my usual Ghostery + uBlock + HTTPS Everywhere + Smart Referer + ScripSafe.
Of course, I'm keeping DDG as my default search engine though ^^

@previous review author: Startpage still uses Google under the hood (it's basically an "anonymous" proxy towards Google), so IMHO DDG is way better as it doesn't feed Google data. Startpage can still be interesting when you really really want to use Google but still want it to be slightly more private than the normal way of using it.