I read Curtis Sittenfeld's first novel, Prep, earlier this year, and it earned a place on my personal "best first novels" list. Her second book, The Man of My Dreams, avoids the archetypal "sophomore slump," but it didn't hit me in quite the same way. One reason for that is probably the choice of third-person narration in this novel, which always has less of a sense of immediacy to me. Another, and probably a larger factor in my perception, is that Sittenfeld's evocation of Lee Fiora's adolescent feelings in Prep felt true regardless of one's high-school experience, whereas Hannah Gavener's life as a single college student and young adult wasn't much like mine, and was harder for me to relate to.
Hannah has a self-protective instinct arising from growing up in an unstable family, one where her parents' divorce, though difficult, was also somewhat of a relief. She frequently compares herself to her older sister Allison and cousin Melissa (better known as Fig), as well as most of the other girls and women she knows, and doesn't feel she measures up. Her relationships with guys don't develop too far, because she's either not sure or afraid of what she thinks she wants from them. Thinks is the main point here, since Hannah tends to engage with her ideas of the people in her life rather than with who they really are. Eventually, she does come to understand that the "man of her dreams" is getting in the way of her reality.
Hannah does grow over the course of the novel, and it's well-written and developed, but I think she irritated me sometimes because she wasn't an adolescent, but still frequently conducted her life and relationships as if she were. I don't mean that in the sense of childish behavior, but more in the way that she held to her images of people in her life, reacting to those instead of their actual quirks and personalities. In all honesty, I've also been guilty of that (and it was tough to unlearn it), so that's probably part of why I found it irritating.
I didn't find The Man of My Dreams to be as absorbing as Prep, and at times I got a bit impatient with it, but overall I still found it be an engaging (and relatively quick) read.