Actually, it's not 100% wikipedia. It displays smart information on top.
I remember searching for an apache httpd configuration directive last week, and DDG showed a snippet of the documentation on top. It was exactly what I was looking for. It's slightly smart, and rather helpful in general.
Personally, I use DDG as my primary search engine. But when I need to look for very specific issues (why is my commanlink not working with X and Y in JSF), I find that google gives better results. Google still works better if you have lots of keywords or long sentances, but otherwise DDG is enough.