Very thorough, and very well written. There is a metric ton of new features and other cool odds and ends in iOS 5, but I think this intro paragraph from Dan sums up what exactly is so hallmark about today’s software updates:
With iOS 5, Apple’s theory of the post-PC era finally moves into practice. No longer are iOS devices second-class citizens, tethered to the sinking anchor of a personal computer. With iOS 5, it’s possible, for the first time, to use your iPhone, iPod touch, or iPad as your one and only device.