Apple fans queued in Asia, Europe and North America for the new iPhone 5, which appeared set to break sales records despite lukewarm reviews and complaints about its mapping system.
The lines of thousands of eager buyers outside Apple stores on Friday looked set to make the latest iPhone a huge commercial success for the trend-setting US tech giant. Some analysts say Apple may sell 10 million in just the first days of the launch.
Australians were the first to get their hands on the device.
In Sydney, faithful fans filmed the experience on their iPhones and iPads as staff inside clapped and cheered when doors opened at 8am.
Companies looking for publicity took advantage of the media frenzy accompanying the launch, with the first dozen or so in the queue wearing promotional T-shirts or carrying advertising materials.
"Seven of us are here from our company, since midday Tuesday," said Todd Foot, 24, who was first in the line and works for an organisation that reviews mobile phones.
Crowds also formed outside Apple's many stores in the US.
"I've been waiting for eight days, I'm so happy right now," said Keenen Thompson, one of the first among several hundred people outside the Apple store on New York's Fifth Avenue.
The first in line at Montreal's Apple store was Jonathan Moreau, 28, who said he would replace his iPhone 4s "which I don't use for work, but just for me." The new model, he said, "is faster, with a better display, a better camera."
At the Apple store in Bethesda, Maryland, Kirsten Mentzer, a university student who came with her sister and parents to get the new gadget, secured the first spot.
"It's fun to spend time with other Apple friends," she said. "I've always been part of the Apple community. My parents raised me on an old MacBook."
Mike Bishop of Bethesda said he was "really excited" about the new iPhone and had been waiting to replace his broken iPhone 4.
Asked if he would consider another phone, Bishop said: "Once you use an iPhone, you don't go back to any other brand. The main thing is the refinement at every level."
At Apple's store on London's Regent Street, Richard Wheatcroft and George Horne camped out for a full seven nights to promote their bakery, staffed by victims of domestic violence.
"We decided to buy four iPhones and auction them off. Anything raised will go towards the bakery," Wheatcroft told AFP.
Compared to the iPhone 4S, Apple's new smartphone boasts a bigger screen, stronger battery and faster connection to the latest 4G networks.
It is lighter and slimmer, and its operating system iOS 6 contains tweaks designed to improve the user's experience.
But many analysts say Apple has fallen short as other companies such as Samsung improve rival offerings powered by Google's Android operating system.
"Unless Apple ups its device innovation game, we may be seeing Apple's iOS empire approaching its zenith," said Tony Costa of Forrester Research.
Apple also faced a barrage of criticism after it ditched Google's maps application in favour of its own program, riddled with errors. Many users protested that the new maps misplace some landmarks and leave others off altogether.
But enthusiasm among early-bird shoppers was undimmed as stores opened in Japan, Hong Kong, Singapore, France, Germany, Britain, the United States and Canada.
Ryoho Yamashita, a 23-year-old student, had queued since midnight outside a Softbank store in Tokyo and said there had been a celebratory atmosphere among those waiting.
"It's like a festival that I enjoy every year," he said.
In France, Apple's flagship Paris store was doing roaring business as a threatened strike by workers over a pay dispute failed to materialise, while some fans in the Netherlands were heading across the border to shop in Germany.
London police, meanwhile, were seeking a Pakistani shop assistant over the theft of 252 of the phones from a store in Wimbledon, south of the British capital.
The phone's first rollout is in nine countries, with Apple planning to sell it out in 100 countries by the end of the year.
Apple shares rose to new record highs, gaining 0.8 per cent to $US704.67 ($A678.25), boosting the market cap of the world's most valuable company to nearly $US660 billion.
Ben Reitzes, a Barclays analyst who attended the New York launch, said he was "positively surprised regarding the pace of the rollout."
"Given indications for demand, iPhone sales this weekend should far surpass prior sales records, although we acknowledge the risk that supply constraints and stock-outs could cause the record figure to actually be lower than it really should be," he said.