Great shows, in my opinion, allow you to sympathize with characters and find a connection with them, even if they or their life situations are completely different from your own. As a good show, Girls allowed me to connect and sympathize with characters because, at many points in the show, their lives reminded me of my own.
People have criticized Girls for attempting to be the "voice of our generation." I don't think it's a voice of any generation, and neither do I think Lena Dunham intended it to be so. She told a story that reflected her own experiences as a young twenty-something wannabe artist, and something about that voice resonated with me, whether I'd like to admit it or not. Girls presents a cynical, painful look at life in New York as a recent college graduate, dealing with friends and relationships and insecurities and career ambitions that never quite work out. It's not a particularly flattering portrayal, and it does not provoke laughs, despite being labelled a "comedy," but its bleak episodes present one form of the post-college life in an unflinchingly real way.
The protagonist, Hannah, often comes off as arrogant or selfish, but this unintentional attitude covers up the fact that she is deeply, paralysingly insecure. She hates herself more than anybody else could hate her, and she worries constantly that her writing is insignificant, that she is going to be a failure, and that she deserves nothing else. She has a broken, needy relationship with a boy who initially does not seem to respect her, a fraying relationship with her best friend Marnie, and has bounced from unpaid internship to unpaid internship before finding a not-so-fulfilling job in a coffee shop. She's definitely not always likeable, but she feels so real, in a painful, I'm-not-sure-I-want-to-look kind of way.
Her best friend Marnie, meanwhile, is determined to be grown up and sophisticated, for everything to fall into its neat little place, and cannot cope when it doesn't. Despite everything being exactly as she would like at the beginning of the show, she's deeply dissatisfied, although not fully ready to admit it. Finally, their friend Shoshanna suffers from total word-vomit, is completely neurotic and anxious, and finally gets pissed at the end of the season that no-one seems to respect her or take her seriously. I love her character, because it's a far more realistic look at the "comedy ditzy girl," where she is shy and insecure and socially awkward, to the point of often being unbearable, but she's still a person with goals and desires who feels crippled by her own insecurity.
There's also Jessa, a "free-spirit" adventuring type, but her story was the only one that didn't feel authentic to me. Perhaps her character is realistic to other people, but unlike the others, I have never met anyone quite so selfish and ungrounded and impetuous as she is, so her plotline (and particularly the way it ended) didn't resonate with me.
I don't think that Girls is a show that you can either "get" or "not get," or that it's hipster-cool to like it, or that everyone should enjoy this admittedly uncomfortable and bleak show. I also don't think it's a perfect show; far from it. But despite the fact that every character is unlikeable on some level, I see elements of them and their lives all around me, and I am looking forward to that exploration continuing next season.