Some things I really liked about the movie:
One, the fact that Dunham, who does not have, shall we say, a supermodel's body, regularly appears in her underwear, or with somewhat blotchy skin, or greasy hair. And has scenes in the movie where she explicitly confronts the fact that people refer to her as fat. And she says it makes her feel bad, but she also doesn't make a big deal out of it. The scenes of her half naked in the movie are there, it seems, for the purposes of realism, not to make some kind of statement. And man, it's nice to see thighs on the big screen.
Two, the characters, who are over the top and ridiculous, but still completely believable. There's a degree of restraint in how larger-than-life she lets them be, and it's brilliantly balanced.
Three, spoiler alert, the whole thing with the jerk chef. He's a jerk, you know it and Lena knows it, but you also both know that she's going to sleep with him (and the film does a great job portraying the lead-up to that, the sense of slight excitement that always accompanies seduction), and that it's not going to work out well. And indeed, they have sex, lousy sex, albeit with some adventure involved, and she feels crappy afterwards. Not traumatized, not raped, not my-life-is-ruined, just crappy. It's so wonderfully true to life, in the sometimes you do dumb things even though you know they're dumb, and you feel kind of wretched about it, but in the grand scheme of things, it's ok. It's not the central plot point of the film, even though it's positioned as if it were a climax - it's just kind of another thing that happens.
Four, her relationship with her mother, especially the physical side of it. I feel like it's pretty rare that parents and children are really physically affectionate on screen, and maybe the world would be a better place if they would.
Overall - it's great. Check it out. And then read the New Yorker piece, because you'll come to love Lena Dunham even more. But don't read it beforehand (though I did), because you'll probably appreciate the movie more if you don't know most of the plot beforehand.