I'd describe this book as an interesting yet flawed work- it raises some interesting questions, but often fails to follow through with incisive analysis.
Any book that attempts to describe "a generation" is going to raise objections of over-generalization and, therefore, anyone who writes such a book really should start by explaining just why, exactly, this is a useful characterization. At a minimum, there are problems of periodization, inclusiveness, and timeliness.
Some generations have been shaped by world-historical events (e.g., WWII, Cold War, Great Depression) but, since that does not seem to be the case here, then why define a generation as beginning in 1973 instead of 1982, or 1989? And, although the author beats pretty hard on the diversity drum, her observations often seem entirely centered on her own white, liberal, upper-middle-class self. Perhaps that's inevitable, but, if her "generation" generalities do not include those who are non-white, non-liberal, or non-middle-class then she should explicitly say so.
The primary thesis of this book seems to be that a sort of extreme individualism is characteristic of her "Generation Me." One problem with this is that it may be too soon to say- after all, a similar survey of young adults in 1928 might have reached similar conclusions, yet a survey of the same people in 1948 might well have discovered a greater accommodation to collective action and personal sacrifice. Also, she seems to define "generations" largely on the basis of a shared common popular culture without any apparent awareness that conformity to an omnipresent, highly commercialized popular culture just might be antithetical to a more authentic individuality.
The book seemed particularly weak in discussing family and marriage. There seems to be a good deal of evidence that, on average, married people are healthier, wealthier, and happier than otherwise-similar singles- and that the reason for this is that the relative permanence and security of marriage promote a commingling of assets and labor specialization- a co-dependence, if you will- that is seldom found among non-married co-habiting couples. Yet, duty and obligation- even if mutual, and voluntarily assumed- surely restrict one's absolute freedom! And so, this book would have been far stronger had the author explored the trade-offs between the freedom to do whatever, whenever against the the freedom to voluntarily bind oneself to durable commitments of duty and obligation to others.
In all, I wouldn't characterize this as a bad book- just an unfinished one. It does raise important questions.