While the most obvious change in iOS 7 is the look and feel of the user interface, Apple's engineers have packed the update with numerous changes both big and small.
Here are a selection of changes noticed by folks in the MacRumors Forums and elsewhere.
Cellular Data Tracking by App - In Settings / Cellular, users can track cellular data usage on a per-app basis. Apps can have their cellular data access disabled individually as well.
Update Apps Manually - The App Store now updates apps automatically, but for users who prefer to handle things themselves, automatic updates can be disabled via a slider in Settings / iTunes & App Stores.
How to Get to Spotlight - Spotlight is now accessible from the home screen by swiping down from the middle of the screen. Additionally, in Settings / General / Spotlight Search, users can manually turn search result categories on and off, as well as change the order results are presented in.
Live Clock Icon - The clock icon provides the correct time, including a live second hand. The weather app does not update -- it is always partly cloudy.
Newsstand Has Permanent Icon - Newsstand's icon remains the same regardless of what publications are inside it. The app itself works similarly, though the design is substantially different. Newsstand can now be put inside a folder as well.
App Permission for Microphone Access - Apps are now required to ask permission to access the microphone, similar to how apps currently ask to access location data or the camera.
Multitasking Switcher Works in Landscape - The app switcher works in landscape mode. Double-tap the home button to access. Control Center can also be used in landscape. Apps can also be manually quit by swiping up, and multiple apps can be closed at the same time...
Read the full story here. Source: Mac Rumours