AnandTech has released some benchmark tests for the iPhone 4s. The data shows that the dual-core processor added in the iPhone 4s has drastically improved performance over the iPhone 4. The iPhone 4s with a clock speed of 800 MHz performs just under the performance of the 1GHz processor in the iPad 2 running iOS 5.
The iPhone 4s has a lower yield battery than the iPad 2 running at 5.25 Watt hours. With the lower clock speed of the A5 chip in the iPhone 4s the battery can be smaller than the iPad 2 battery.
Its funny how the iPhone 4s is out performing many of the other smartphones on the market with its limited RAM 512Mb and 800 MHz processor compared to others that have 1GB ram and 1Ghz processors. The iPhone 4s can easily render any game title at 30 FPS or higher.