The much success of "Downton Abbey"

           Over the weekend I heard about a T.V. show called "Downton Abbey", appparently a very popular show. Anyways, I asked my friends about this show and recieved many positive comments about it. Not only were my friends  hooked onto to this show, but many parents are big fans as well. One of my good friend even mentioned that her dad left a dinner party to come home and watch the finale of "Downton Abbey".  After hearing all of the commotion about this show, I started to wonder why was "Downton Abbey"so well-liked?
          From only watching one episode, I could not tell you a whole lot on what it is about. However, from this article I learned that this show contains "stories [that] are about emotional situations that everyone can understand” and "it deals with timeless themes such as, social rankings, money,  and homosexuals". 
      Many of these "timeless themes" mentioned are big themes practiced in American culture, and as such, I wonder is that why this show has become so accepted, because Americans can just connect with it? Hoever, the show does take place in the 20th century in Britian, so how much can Americans connect with it? 
      In any case, what do you think makes a T.V. show become so popular in America? What must it contain to make it well-liked? Are there any common themes between "Downton Abbey" and other popular shows like "Modern Family" or "Homeland"?