The iPhone 4s adds more than just Siri (which I never use):
Dual Core Processor
Vastly improved graphics performance
Up to 64GB Internal Storage
8MP Camera
1080p Video recording
Bluetooth 4.0 (Low power bluetooth)
For me, the biggest improvements are the 64GB storage and 8MP Camera which is good enough outdoors for me to leave the P+S at home
Dual Core Processor
Vastly improved graphics performance
Up to 64GB Internal Storage
8MP Camera
1080p Video recording
Bluetooth 4.0 (Low power bluetooth)
For me, the biggest improvements are the 64GB storage and 8MP Camera which is good enough outdoors for me to leave the P+S at home