I'm on my third iPhone 4 at the moment. The first iPhone 4 I purchased lasted two weeks until a battery defect overheated the hardware and would no longer hold a charge. The Genius replacement iPhone 4 that I swapped out had a hardware microphone defect that I noticed hours after leaving the store. When I got a call, the person on the other end couldn't hear me unless I activated the speakerphone. To further test the problem, the phone would not record sound and take voice commands, however the remote headphone mic worked just fine. I'm on my third phone now, going one week strong.