Both Google and DuckDuckGo have their share of great search options. One of DuckDuckGo's best features is the !Bang option that allows you to search and redirect to any site automatically. DuckDuckGoog essentially adds that option to Google.
When you perform a normal search on DuckDuckGoog, it automatically searches (encrypted) Google for results. However, if you add the !Bang (example: !amazon Nicolas Cage), then DuckDuckGoog searches the site (in this example, Amazon) you type in and takes you to the results immediately.
The !Bang search is one of DuckDuckGo's handiest features, so it's nice to have the option to do it directly from a site that would otherwise search Google. If you enjoy DuckDuckGoog, it's also easy to make it your default search engine.