Days before the official publication on Tuesday, disclosures from the book dominated headlines and airwaves after a Spanish-language version of the memoir mistakenly went on sale in Spain.
Revelations such as how heir to the throne Prince William allegedly pushed Harry to the ground in a 2019 row to how he lost his virginity, took drugs and killed 25 people in Afghanistan prompted both condemnation and derision.
Writer A.N. Wilson called the ghostwritten tome -- the biggest royal book since Harry's mother Princess Diana collaborated with Andrew Morton for "Diana: Her True Story" in 1992 -- "calculated and despicable" and a work of "malice."
"Having made the idiotic decision to 'go public' about his rift with the royal family, Harry was no doubt under enormous pressure... to spew out as much poison as possible," he wrote in the Daily Mail.
"But it has cast him in an appalling light. And whatever he intended, it makes us sympathize not with him, but the Royal Family."
The book is the latest hostile blast from Harry and his American wife Meghan after they quit royal duties and moved to California in 2020.
The Duke and Duchess of Sussex, as they are formally known, have since cashed in on their royal connections with several lucrative contracts for tell-all books and programs.
The Spanish-language version of the book was hurriedly withdrawn from shelves after the blunder on Thursday but not before it had been purchased by media outlets, wrecking the publisher's strict worldwide embargo.
The Sun tabloid said that while people sympathized with Harry, 38, over the trauma of losing his mother as a child and having to grieve in the public eye, "neither can justify the destructive, vengeful path he has chosen, throwing his own family under a bus for millions of dollars".
In an editorial, it pointed to "countless discrepancies" in his claims and urged him to listen to friends who have urged him to "stop for his own good".
The Guardian's Gaby Hinsliff said the book had moved beyond issues of "awkward public interest" into the "washing of dirty linen" in public.
The US edition of the left-leaning newspaper, which has questioned the monarchy's role in modern Britain, was the first to publish a leaked extract of the book this week in which Harry described his physical altercation with William.
"The details of the brothers' alleged punch-up in a palace cottage are at once almost ridiculously trivial and heartbreakingly sad," she wrote.
- #ShutUpHarry -
Harry's claim to have killed 25 people in Afghanistan and likening his targets to removing "chess pieces" from a board, has been seen as boastful and inappropriate, and enraged some veterans.
Retired colonel Tim Collins, who led a British battalion in Iraq in 2003, condemned a "tragic money-making scam", adding: "That's not how you behave in the army, It's not how we think."
"Harry has now turned against the other family, the military, that once embraced him, having trashed his birth family," he added.
Senior Taliban official Anas Haqqani tweeted: "Mr. Harry!" The ones you killed were not chess pieces, they were humans; They had families who were waiting for their return."
As the hashtag #ShutUpHarry began trending on Twitter, The Sun quoted sources close to his father King Charles III as saying he had been saddened by the book.
But there was no official palace comment.
The only previous royal reaction to Harry and Meghan's complaints was after they accused an unnamed member of the royal family of racism in their 2021 interview with Oprah Winfrey.
William told a reporter the family was "very much not a racist family" while his late grandmother Queen Elizabeth II famously said "recollections may vary".
Craig Prescott, a constitutional expert at Bangor University in north Wales told AFP the "scale" and "ferocity" of the current royal rift was unprecedented but that the royal family would probably "ride this out".
And he ruled out any moves to remove Harry and Meghan's royal titles, which would require political intervention and new legislation.
The royals would likely regard that as "pouring fuel onto the fire" at a time when they wanted to focus on Charles's looming coronation on May 6, he said.