DuckDuckGo promises to be more privacy friendly. They say they don't track you and they don't show targeted ads, only keyword related ads.
This is something we all take into account, we usually do not care about our privacy, I think is because we are not aware (physically) that we are being observed, and other times is because we think that we have nothing to hide, but we actually have and should care about it.
Another cool feature for programmers: DDG has much better StackOverflow integration. When you search for something programming related, they often show a snippet on the side with the top answer from StackOverflow. It makes copy pasting sooo much easier.
This is true, DDG usually shows better responses if you are a developer, the pages at the top are usually specialized forums or blogs, and less mainstream blogs full of ads.
If you think it's funny that an ex-Googler uses DuckDuckGo, you should have seen the faces of my colleagues at Google when they saw that I was using DDG at Google. And even funnier was when my manager noticed this and then we had a discussion about why he doesn't use it: local queries (searching for nearby restaurants for example) were not working very well in DuckDuckGo and he used them very often.
I have also noticed this, I tried to use DDG as my primary search engine on my phone, and I had to go back to Google, just because of that, I can use it on my PC, because on it I usually search for answers to technical questions, but on my cell phone I usually search for places, and then DDG is not better or even equal to Google, the problem is that because Google is more convinient, we accept to let it know everything about us.
It is good to know that DDG is addressing the problem with an opt-in location sharing option.