Now, as COO of Facebook, she has been part of another phenomenon, a company that now claims more than a billion users. Sandberg holds close to 2 million Facebook shares and has options on millions more, according to the company's 2012 stock filing. She and her husband, SurveyMonkey CEO David Goldberg, share a brand-new 9,000-square-foot mansion.

So of course she can leave work at 5:30 to take care of her two kids. After all, she's the boss.

But for all her apparent wealth and power -- for all her success -- Sandberg appears to remain the rather retiring person she was in high school and college, the kind of person who "did not speak or raise her hand," writes Auletta.

"I never thought I would write a book," she says in "Lean In." She decided to do so only after years of discussion with colleagues. She defines "leaning in" as "being ambitious," and it's an assertion she appears to make hesitantly because the stakes are so large.

Now that "Lean In" is out, said MIT business professor Lotte Bailyn, Sandberg should use her bully pulpit to push workplace changes -- not just for women, but men as well. The typical workplace is the way it is because we accept our endless days and constant deadlines as the norm. We need less rigidity, more creativity, more room for work-life balance, she said.

"The problem isn't about fixing the women. The problem is about gender roles and dynamics and the expectations and norms that exist in the workplace," she said. "As long as we keep emphasizing how to fix the women, I don't think we're going to get very far."

Michigan's Whitman agreed that Sandberg can help change the dialogue. "Absolutely Sheryl Sandberg is right to encourage women to have more self-confidence," she said. "But I also think it's wrong to define success for women in terms of how many Sheryl Sandbergs we can produce. What is more critical is what can we change to make the balance less difficult for that much larger host of women who work not for self-fulfillment, but because they have to."

For now, though, Sandberg has made her statement. As for all the criticism? Something she told Auletta two years ago suggests she's probably wondering why all the fuss is about her, and not the bigger issues.

"I feel really grateful to the people who encouraged me and helped me develop," she said. "Nobody can succeed on their own."