I agree that a faster processor, Siri, and iOS5 are "key" features and worth an upgrade. However, a key feature not mentioned is the improved performance of both cellular and WiFi data transmission. Running SpeedTest from my iPhone 4S and comparing with results obtained using my iPhone 4, I found noticeable increases. Cellular data rates on my 4S reach upwards of 5.5 Mbps down as compared with a previous maximum 2.9 Mbps down with the iPhone 4. WiFi performance is...