Before the novel was released at midnight ET, readers -- giddy with anticipation -- gathered in bookstores around the world for parties, or anxiously checked their tablets and e-readers to see if the book was ready to download.
Hundreds of folks waited for the novel in Monroeville, Alabama, Harper Lee's hometown and the basis of the fictional Maycomb of the books.
Before its release, the big controversy with the book
swirled around the transformation of beloved character Atticus Finch from the moral center of "To Kill a Mockingbird" to a racist in "Watchman."
CNN's Ed Lavandera, who was in Monroeville for the book's launch, said many people in there were "surprised by the twist" and worried how it would affect people's views of "To Kill A Mockingbird."
Those who braved lines quickly got their hands on copies -- and equally quickly posted pictures online with them.
Those who tried to download found their patience tested.
"Still waiting to download #GoSetAWatchman," tweeted CNN's Todd Leopold. "Syncs come up empty so far.."
Finally, with coffee in hand, fans set out to read the book in the early morning hours.
Critics have given "Watchman" a lukewarm reception, but what did the readers think?
The earliest reviews Tuesday morning for "Go Set a Watchman" (from folks who hadn't finished the novel) were mixed.
"Up early to read and now halfway through Go Set a Watchman. It's good and I am enjoying it, but it's no TKAM," tweeted someone with the Twitter handle @MrsLCavalier, whose bio identifies her as an English teacher.
Some were unsure just how they felt.
"10 chapters into Go Set a Watchman and I'm still not sure what to make of it. #GoSetAWatchman," tweeted Armando Testani.
Of course there are those who didn't get what all the hype was about.
"People at a midnight release of Go Set a Watchman make me weep for humanity," tweeted @colonelnemo.