-Ramped up internal processors that boast an A5 chip (same as the 2), a dual-core CPU, and it claims to be twice as fast at CPU tasks as the 4.
-The iPhone 4S also features dual-core graphics and runs up to 7x faster than the previous iPhone.
-Photos are enhanced exponentially, using new sensors, an eight megapixel camera, and is the fastest smartphone camera on the market.
-Videos are also souped up, including 1080P display and seamless integration with Apple’s Airplay.
-This is the first world-friendly iPhone, including both GSM and CDMA support. In layman’s terms, this means you can travel with your iPhone and use it anywhere around the globe.
-Battery life is improved upon as well, as seen in the image below from gdgt:

gdgt iphone 5 event 0441 Why you might want to upgrade to an iPhone 4S

-The iPhone 4S will include support for Siri, the iPhone voice-controlled assistant. Tell it what you want to do and it’ll do its damnedest to make the iPhone 4S make it happen. It’ll also read all your notifications to you, not unlike one of the secretaries in Mad Men. Siri will also be available as part of the iOS 5 upgrade. You can read up more specific details on Siri here.

The iPhone 4S will be available in black and white versions on October 14th with a 16GB costing $199, 32GB for $299, and the 64GB for $399.