Well, most of the time I already know the site best suited for my queries (e.g., SO for programming, amazon for shopping, wikipedia for facts, Wolfram Alpha for calculations etc), so DuckDuckGo's bang syntax really comes in handy. Google is astonishingly good at parsing vague queries, but otherwise DDG or Bing are pretty much OK.
I've tried using Bing several times in the past just to give them a fair chance, but every time came back to Google. They are really not at par in the search business. Actually no other company except Google got hold of the nerve of internet searching.