In the first week following its release, A Thousand Splendid Suns sold over one million copies, becoming a number-one New York Times bestseller for fifteen weeks. Time magazine's Lev Grossman placed it at number three in the Top 10 Fiction Books of 2007, and praised it as a "dense, rich, pressure-packed guide to enduring the unendurable." Jonathan Yardley said in the Washington Post "Book World", "Just in case you're wondering whether Khaled Hosseini's A Thousand Splendid Suns is as good as The Kite Runner, here's the answer: No. It's better."
A Thousand Splendid Suns received significant praise from reviewers, with Publishers Weekly calling it "a powerful, harrowing depiction of Afghanistan" and USA Today describing the prose as "achingly beautiful". Lisa See of The New York Times attributed the book's success to Hosseini "[understanding] the power of emotion as few other popular writers do". Natasha Walter from The Guardian wrote, "Hosseini is skilled at telling a certain kind of story, in which events that may seem unbearable - violence, misery and abuse - are made readable. He doesn't gloss over the horrors his characters live through, but something about his direct, explanatory style and the sense that you are moving towards a redemptive ending makes the whole narrative, for all its tragedies, slip down rather easily."
Cathleen Medwick gave the novel a highly positive review in O, the Oprah Magazine:
"Love may not be the first thing that comes to mind when you consider the war-ravaged landscape of Afghanistan. But that is the emotion—subterranean, powerful, beautiful, illicit, and infinitely patient—that suffuses the pages of Khaled Hosseini's A Thousand Splendid Suns. As in his best-selling first novel, The Kite Runner, Hosseini movingly examines the connections between unlikely friends, the fissures that open up between parents and children, the intransigence of quiet hearts."
The New York Times writer Michiko Kakutani wrote a more critical review, describing the opening as "heavy-handed" and early events in the novel as "soap-opera-ish". Despite these objections, she concluded, "Gradually, however, Mr. Hosseini's instinctive storytelling skills take over, mowing down the reader's objections through sheer momentum and will. He succeeds in making the emotional reality of Mariam and Laila's lives tangible to us, and by conjuring their day-to-day routines, he is able to give us a sense of what daily life was like in Kabul — both before and during the harsh reign of the Taliban." Similarly, Yvonne Zipp of The Christian Science Monitor concluded that A Thousand Splendid Suns was ultimately "a little shaky as a work of literature".
The depictions of the lead female characters, Mariam and Laila, were praised by several commentators. John Freeman from The Houston Chronicle found them "enormously winning" while Carol Memmott from USA Today further described them as "stunningly heroic characters whose spirits somehow grasp the dimmest rays of hope". Medwick summed up the portrayals: "Mariam, branded as a harami, or bastard, and forced into an abusive marriage at the age of fifteen, and Laila, a beauty groomed for success but shrouded almost beyond recognition by repressive sharia law and the husband she and Mariam share. The story, epic in scope and spanning three decades, follows these two indomitable women whose fortunes mirror those of their beloved and battered country—'nothing pretty to look at, but still standing'—and who find in each other the strength they need to survive."
Jennifer Reese from Entertainment Weekly dubbed Rasheed "one of the most repulsive males in recent literature". Lisa See wrote that, with the exception of Tariq, "the male characters seem either unrelentingly evil or pathetically weak" and opined, "If a woman wrote these things about her male characters, she would probably be labeled a man-hater."