iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
iPhone 4S Photos Begin Appearing on Flickr, Comparisons with iPhone 4
iPhone 4S on left, iPhone 4 on right
iLounge have also posted a number of comparison shots between the iPhone 4 and iPhone 4S cameras, including this pair of shots of peacock feathers. Left is the iPhone 4S, right is the iPhone 4.
Image courtesy iLounge