Up until recently, Sims has been regularly lauded as the father of gynecology and had worked to repair fistulas, though Hallman uncovered his radical experimentations on enslaved men and women to read "like snippets lifted from the pages of a horror story," questioning Sims's altruism due to his feelings of disgust at diseases of the female pelvic region.

Say Anarcha: A Young Woman, a Devious Surgeon, and the Harrowing Birth of Modern Women's Health was published in June 2023, and was widely praised.

"[12] The Brooklyn Rail called the book "an instant classic" and "a new masterpiece"[13] and noted that "Hallman had done what no scholar had previously succeeded in doing, namely unearthing information about Anarcha independent of Sims's tendentious accounts of her life.

"[19] For The Devil is a Gentleman, a book about the nature of fringe religions, Hallman was interviewed by Jennifer Shahade of Bookslut about his participation in belief systems that he's sure he won't adhere to.

[21] The San Francisco Chronicle called Hallman's chapter about the Texan Christian Wrestling Federation "a small masterpiece of first-person reportage.

"[22] In 2010, Hallman spoke with famed literary critic Parul Sehgal for Publishers Weekly about his nonfiction travelogue which explores modern-day utopians,[23] which was described as "funnier, wiser, sadder, and, surprisingly, more hopeful than Thomas More's misunderstood classic," by writer Jeff Sharlet.

The Utne Reader states that in the conclusion of the book, Hallman says that is "the very idea of utopia that is importance even when it doesn't work in practice.

In The New York Times, Hallman was described as one who "reconfigures our everyday errors and flaws into deeply affecting fiction...[he] is wonderfully bright.

In The LA Times, author and critic Steve Almond stated that "like Kafka before him, [Hallman is] on the make for the sturdy truths in an era of spiritual dislocation.

Hallman's book B & Me was called "a fascinating thing to behold: literary criticism that's deeply personal, hysterically funny, and starkly honest" by Jeff Turrentine at The Washington Post[28] and in the San Francisco Chronicle, Joseph Peschel claimed he "fell in love" with Hallman's book.

[33]" Hallman received a McKnight Artist Fellowship in fiction in 2010, and the John Simon Guggenheim Foundation in the general non-fiction category in 2013.