Nickel and Dimed fits clearly in a tradition of investigative journalism where the writer infiltrates a marginalized group, posing as one of them to find out what life is truly like. The best-known examples of such works are Jack London's People of the Abyss, George Orwell's The Road to Wigan Pier, and John Howard Griffin's Black Like Me. All are mentioned by various critics when assessing Ehrenreich's book.

Many critics praise Ehrenreich for writing about the plight of the working poor, calling attention to a facet of America that is often overlooked and underrepresented. Joni Scott from the Humanist considers the book an "important literary contribution and call to action that I hope is answered." Scott also states that the book "should be required reading for corporate executives and politicians." In Off Our Backs, Kya Ogyn notes that the author "succeeds beautifully" in demonstrating that "the problem lies in the system of low-paid work, not in the workers."

Moreover, Ehrenreich does this with an approach and style that make her topic engaging. As Steve Early notes in the Nation, "Ehrenreich has long been a rarity on the left—a radical writer with great wit and a highly accessible style." Scott Sherman, writing for the Columbia Journalism Review, is among those who see Nickel and Dimed as an evolution in Ehrenreich's abilities as a writer:

For Ehrenreich, Nickel and Dimed is something of a literary triumph. Her essays, while frequently incisive and hilarious, seem one-dimensional when read in large doses. And while her books are absorbing and original, the writing isn't always stylish. Nickel and Dimed, however, shows us a veteran journalist at the very top of her game. The book has a sturdy architecture: four tight, compact chapters in which the prose achieves a perfect balance between wit, anger, melancholy, and rage.

However, some have questioned whether Ehrenreich's work does anything more than state the obvious. As Julia M. Klein writes in the American Prospect:

In the end, what has she accomplished? It's no shock that the dollars don't add up; that affordable housing is hard, if not impossible, to find; and that taking a second job is a virtual necessity for many of the working poor. Ehrenreich is too busy scrubbing floors to give us more than a passing glimpse of the people in that world.

Jane Yager, writing in Dollars & Sense, raises another issue. Although the book is an effective portrayal of low-wage living, Yager states, "It's hard to figure out what the book aims to accomplish." Beyond making wealthy readers feel bad, "the book offers no specific directives for what the now-properly-chastised affluent reader should do."

Several other criticisms have also been raised. Yager notes that the idea of a well-off woman pretending to be poor "could easily seem self-indulgent and offensive" in much the same way that Black Like Me has been criticized. In addition, Yager points out that readers may leave the book with the misguided notion that "if American low-wage workers are worse off now than they were 30 years ago, this must just be because bosses have become nastier individuals." Also, despite her recognition of Ehrenreich's accomplishments, Ogyn states that "the book contains numerous disdainful comments" about overweight people.