However, not all devices eligible for the update will receive all features. Several new features are available only in select devices and select regions. If you are concerned whether your old iOS device will be receiving a particular functionality with the new upgrade, this list should clear your doubts.
The panorama feature in the Camera is available only on iPhone 4S, iPhone 5, and iPod touch (5th generation). Also, square and video formats and swipe to capture are available on iPhone 4 or later, iPad (3rd generation or later), iPad mini, and iPod touch (5th generation).
The newly added filters that lend Instagram like features to the Camera app will be available on iPhone 5 and iPod touch (5th generation). However, filters for the Photos app will be available on iPhone 4 or later, iPad (3rd generation or later), iPad mini, and iPod touch (5th generation).
The wireless file sharing solution that was previously available only on the OS X came to the iOS with the introduction of iOS 7. AirDrop can be used to share content wirelessly with people around you using Wi-Fi and Bluetooth. The feature however will support only iPhone 5, iPad (4th generation), iPad mini, and iPod touch (5th generation) and requires an iCloud account.
Apple's personal voice assistant Siri has been a popular companion on iOS devices. With iOS 7, Apple introduces new commands as well as Bing, Twitter and Wikipedia integration for Siri. The availability of the features of the voice guide however varies in different countries. It may not be available in all languages or in all areas. Like before, Siri is available on iPhone 4S, iPhone 5, iPad with Retina display, iPad mini, and iPod touch (5th generation) and requires Internet access.
Other new features such as the iTunes Radio or the revamped Safari are part of core iOS 7 and you'll get to enjoy those features as long as your device is amongst those listed above as eligible for upgrade.
Also See: 10 big improvements in Apple's iOS 7