Comparing the video shots from the iPhone 5 vs. iPhone 4s
This video looks at indoor and outdoor light, front and rear camera, depth of field & also notice the difference in stabilization.
Both iPhones were handheld on top of one another to have equal comparison
All Video has not been altered other than cropping/sizing
iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.