It definitely gets substantially funnier; it also gets easier to like or at least sympathize with Hannah, if not the others. It might be that Lena Dunham is only good at writing her own character but there might be something deeper happening there.
I'll also say that if you've ever wanted to see the mom from Freaks and Geeks get naked, here's your show.
I think Shoshannah has become fairly sympathetic while the latest episode did a lot for Adam (the second best character on the show next to Hannah) in that regard as well. It's been hard caring about Marnie or Jessa though. Especially Jessa.
The difference there I think is Marnie is a girl who's being shitty in a way that is familiar, that just about every long-term relationship (even the successful ones that end with cake and babies) has had a moment in which one or both parties has felt at least the urge/temptation to be shitty in exactly that way. Whereas Jessa is being shitty in a way that is most reminiscent not of the average person's experience but of the Manic Pixie Dream Girl archetype - but, critically, the dark side of MPDGs, the "be spontaneous and individualistic without actually being of value to anybody or anything" side - which makes her both unsympathetic AND unrelatable, which in turn makes her the devil. Looking at her that way makes me respect the work put into the character even as I fucking loathe her and hope she gets hit by a truck in the season finale.