iOS 7 looks totally different than iOS 6, and most App Store apps are going to have to undergo a big design overhaul to fit it. Gone are the rich textures and deep garnishes. Corinthian leather has been replaced with Gaussian blur. A lot of iOS 6 apps look instantly out of place.
There are, however, quite a few popular apps that look like they belong in iOS 7. Whether it’s by coincidence or intentional forethought, these 16 iOS apps fit in with iOS 7 very well already:
Letterpress

Twitterrific
Rdio
Vesper

Clear
Dots
VSCO CAM

Vine
Yahoo Weather

Dropbox
Mailbox

Pretty much all of Google’s iOS apps look great. Some examples:
Google+
Google Maps
Gmail
Google Search
Hangouts
