I'm unfortunately in the same boat, but I think it does also depend on what you're looking for. I'd wager that if a lot of people had their default search engine changed to DDG, they'd probably fine. Let's be real, "facebook" and "facebook.com" are very common searches because most people have forgotten the distinction between a search bar and an address bar, so typing URLs in a Google/MSN search is probably a solid third of their traffic. DDG would probably be just fine for this sort of thing; people sure didn't notice when their default search got changed to Trivoli or the dozen other browser hijackers that were making their rounds a few years ago.
Where DDG comes up very short, however, is in more specialized searches. If you're looking for a code snippet or an outdated version of some app or something more specific and technical, DDG is a crapshoot at best and useless at worst. I mean, I can't really blame them - Bing is still inferior at this point and they have thrown Microsoft quantities of money at the problem. Search is hard - there was a decade prior to Google where Altavista and Lycos were doing their best with plenty of money and lots of talent, and they were still beaten by Google.
Ironically, DDG might get better relative to Google because Google results have continued their downward spiral toward the lowest common denominator. Just yesterday, I was trying to find out if anyone else with my particular TV was able to get the Android app "AnyRemote" to send the right IR code. I went to Google to search the model number with 'anyremote', and Google seemed to thoroughly ignore the existence of 'anyremote' in my search query, instead showing me physical remote controls, even when I put anyremote in quotes.