Original price: 16GB: $199, 32GB: $299, and 64GB: $399.
While not a complete overhaul, the iPhone 4S did have some improvements over the iPhone 4. Apple released a voice control system, Siri, that can make phone calls, set reminders, write or read email, give directions, report on traffic, and give information about weather, stocks, and definitions.
The phone came with a much faster processor and the option for double the memory. Read more of the specs of the iPhone 4S.