I have been using OS 4 for a couple of months now. It’s amazing how subtle changes can affect the way the whole operating system feels. From the unified inbox to the portrait mode lock, Apple really has taken their time with improving the iPhone experience. I have been using OS 4 on my everyday iPhone 3GS (not recommended) and it’s been quite a bumpy ride (especially when I lost my camera functionality) but using OS 4 everyday has been awesome.
iPhone OS 4: Two Months Later