>>>SquareTrade analyzed iPhone accidents for more than 20,000 iPhone 4s covered by one of its plans and found an 82 percent jump in reports of broken screens in the devices first four months, compared to the first four months after the iPhone 3Gs release.<<<
While the total population of iPhone 4s is obviously much greater than 20,0000, the SAMPLE that these statistics are based upon was about 20,0000 phones, of which about 4% suffered glass breaks.
So, based upon the sample, of those 1.5 million iPhone 4 sold on the first day, about 60,000 of them had glass breaks in the first few months. Perhaps not catastrophic, but 1 in 25 is significant number. Also, the fact that glass breaks are nearly twice as likely with the newer, presumably superior version is not a great sign.