"Everything has been upgraded, literally. It has a better look too," said Joe Duffy, who got in line outside the Apple Store on Fifth Avenue in New York at 4.30 a.m. to buy the new smartphone that is 24 percent thinner than the iPhone 3G and includes 100 new features, PC World reported.

"The screen is so beautiful that you can't even see the dots," said Manayabu Ishiyama, who was waiting in line outside an Apple store in Tokyo to upgrade from his current iPhone 3G S, the magazine said.

The debut, however, has been marred by questionable supplies due to demand that was "far higher" than anticipated, Apple said.

AT&T began taking pre-orders June 15, but suspended that after a day, when the system became swamped with 600,000 pre-orders.

Some were frustrated, but others took it in stride. "I realize there are more important things going on in the world right now, but it's kind of fun to be out here," said Curtis Glavin, a customer in line in Boston.

Copyright 2010 United Press International.