The new model looks similar to the previous iPhone 4, but has an upgraded camera, faster processor, enhanced security and voice-activated software, which lets users ask the phone questions. The voice software drew glowing reviews.
"I had been thinking of this phone for a long time," said Chad Bullar, 23, a New York University student who is buying the phone for its new messaging service and the voice software. "I was going to wait for the iPhone 5, but that seems like a year away, so I got this one."
The phone -- unveiled just a day before Jobs died -- was initially dubbed a disappointment because it looks the same as the last iPhone. But anticipation of the "Siri" voice software helped it set a record with initial online orders on October 7.
Apple CEO Tim Cook and his executive team hope the first device sold without their visionary leader at the helm will protect the company against a growing challenge from the likes of archrival Samsung Electronics.
The South Korean company, which powers its phones with Google's Android software, expects to overtake Appleas the world's biggest smartphone vendor in terms of unit sales for the third quarter.
"(Jobs) made everything better and the products he released were thought through in such detail," Duncan Hoarein London said, after a loud roar greeted the opening of the store. "It was about the beauty of something and the simplicity."
Apple does not release sales on launch day, so gauging initial figures is difficult. However, it took more than 1 million online orders in the first 24 hours after its release, exceeding the 600,000 for the iPhone 4, which was sold in fewer countries initially.