1. Turn-by-turn navigation is available only on iPhone 4S, iPhone 5, and iPad 2 or later with cellular data capability.
2. Flyover is available only on iPhone 4S, iPhone 5, iPad 2 or later, and iPod touch (5th generation). Cellular data charges may apply.
3. Siri is available in Beta only on iPhone 4S, iPhone 5, iPad (3rd generation), and iPod touch (5th generation) and requires Internet access. Siri may not be available in all languages or in all areas, and features may vary by area. Cellular data charges may apply.
3. FaceTime video calling requires a FaceTime-enabled device for the caller and recipient and a Wi-Fi connection. FaceTime over a cellular network requires iPhone 4S, iPhone 5, or iPad (3rd generation) with cellular data capability. Availability over a cellular network depends on carrier policies; data charges may apply.
4. Offline Reading List is available on iPhone 4 or later, iPad 2 or later, and iPod touch (5th generation).
5. Made for iPhone hearing aids require iPhone 4S or iPhone 5.
6. Panorama is available on iPhone 4S, iPhone 5, and iPod touch (5th generation).
7. Find My iPhone and Find My Friends enable you to locate iOS devices only when they are on and connected to a registered Wi-Fi network or have an active data plan.
8. iCloud requires iOS 5 or later on iPhone 3GS or later, iPod touch (3rd generation or later), or iPad; a Mac computer with OS X Lion or later; or a PC with Windows Vista or Windows 7 (Outlook 2007 or 2010 or an up-to-date browser is required for accessing email, contacts, and calendars). Some features require iOS 6 and OS X Mountain Lion. Some features require a Wi-Fi connection. Some features are not available in all countries. Access to some services is limited to 10 devices.
For the complete feature walk through goto: http://www.apple.com/ios/whats-new/