There has been no PR firm involved as far as I know, it is being spread by fans and advertising efforts by the founder. In my experience the results are almost always more relevant than google's, especially the 0-click info. I use DDG mostly for programming-related queries, but also normal searching. I have been using it for 99% of my searching for over a year now. There is also a rather large and devoted user base, partly due to the fact that community interaction from the team has been excellent (in my experience).