The reason I love this show so much is not only because its hilarious, but because it is so REAL. The characters and situations really resonate with my generation especially, as we are all about to face the "real world" after college. Though many critics have had problems with nepotism in the casting (Brian Williams, David Mamet, Bad Company's Simon Kirke), I don't think its a very legitimate argument against the show, since the presence of nepotism is something that everyone has to deal with in any industry. Plus, all of the girls are great actors anyway, so its not like they didn't deserve getting cast. Another controversial factor in the show is that it doesn't feature many characters of color despite taking place in New York City. Dunham said she has made an effort to change this for the upcoming second season. However, the show is loosely based on Lena Dunham's own life, so the characters we see is her own reality.
I think some people love to hate Girls because they don't like seeing a young woman make it as a writer and director in a male dominated industry. The reality is this show is extremely well-crafted and the dialogue is very smart. Dunham's been compared to Woody Alllen in her writing style, which I can definitely see. I'm going to make a bold statement and say that Girls IS one of the best shows out there right now. I would definitely recommend watching the first season, and I can't wait for January!