Despite technical issues, Apple’s launch of the iPhone 4 last week appears to have broken new records. Analyst estimates from Oppenheimer & Co claim Apple sold 1.5 million units in the first day of availability last Thursday, one and a half times as many iPhones as it sold in the first three days of previous launches of the smartphone. Although Apple has not yet officially commented on the early sales, there were 600,000 pre-orders from both Apple and AT&T. Interestingly, Piper Jaffray estimates that 77 percent of those who purchased the iPhone 4 were in fact upgrading from a previous iPhone model (38 percent more than the figure for last year’s 3G S model). “Apple has in three years built brand loyalty in the phone market that compels users to upgrade to the latest version and wait in line for one to six hours to pick up their iPhone,” wrote Piper Jaffray analyst Gene Munster. As far as wooing new iPhone users from other smartphone bases, 6 percent of non-iPhone users were switching from Research in Motion’s BlackBerry, 3 percent from Google’s Android and 2 percent were from Nokia.

Some of the first people to get the device reported problems with discoloration on the screen and antenna reception on the device. Users posted videos online demonstrating how the signal dropped out when they covered the bottom-left corner of the phone with their hand. “Gripping any [mobile] phone will result in some attenuation of its antenna performance with certain places being worse than others depending on the placement of the antennas,” said a spokesman for Apple, according to a Wall Street Journal report. He added that users should avoid gripping the  iPhone 4 “in the lower left corner in a way that covers both sides of the black strip in the metal band.” He said buying a case for the phone also solves the problem. Reports today state that Apple is set to soon release a software fix that will address the problem.