The iPhone 4S just update the CPU to A5 dual core processor currently running in iPad 2. We can see significant increased of performance when using the phone for multimedia use. There are also updated 8MP camera that can record 1080HD video. Also introducing Siri an intelligent assistance which you can get something by asking.
iPhone 4S come with new iOS5 which include more than 200 new features including Notification Center, an innovative way to easily view and manage notifications in one place without interruption and iMessage™, a new messaging service that lets you easily send text messages, photos and videos between all iOS 5 users.