The new interface is said to be “very, very flat,” according to one source. Another person said that the interface loses all signs of gloss, shine, and skeumorphism seen across current and past versions of iOS. Another source framed the new OS as having a level of “flatness” approaching recent releases of Microsoft’s Windows Phone “Metro” UI.
While the look will change, iOS 7 will reportedly remain be easy to use and there is no learning curve for existing users. System apps and functions apparently work similar to how they do now.
The interface changes include an all-new icon set for Apple’s native apps in addition to newly designed tool bars, tab bars, and other fundamental interface features across the system.
Apple is also said to working on a way to add more 'glance-able' information and system options panels. It's unclear how these new views would be implemented; however, one option discussed was to make them appear via swipes from the left and right side of the device similar to how the Notification Center drops down when swiping from the top.
Earlier today, the site also detailed some information about Apple's update to OS X.