Despite sporadic reports of display issues, and significantly more persistent reports of issues with the of the iPhone 4, Apple did not appear to have any problem selling them on launch day.

Piper Jaffray researchers report that yesterday were to existing iPhone users upgrading from a previous model. Combining that with the estimated 1.5 million iPhone 4s sold, it would seem that more than 1.1 million iPhone users jumped at the chance to switch to the redesigned iPhone 4.

The headlines around the iPhone 4 sales appear to focus on that fact--seeming like a thinly veiled attempt to discredit the launch-day success. However, the flipside of that number is that there were nearly 350K new iPhone users as well.

That means that Apple acquired more new iPhone customers than Sprint's overstated --and that is on top of the 1.1 million upgrading iPhone users. It also means that Apple grew its market share by three times more than the on Verizon. If this were any other smartphone aside from the iPhone, the 350K alone would be reason to declare the launch an overwhelming success.

Taking the estimates a step farther, AT&T recently reported that four in ten iPhone purchases were for business use. Assuming that figure holds true--600K of the 1.5 million iPhone 4s sold were for business use, and 140K of those were to new customers that did not previously own an iPhone.