iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
Apple's '12 Days of Gifts' App for 2013 Now Live, Includes U.S. Customers
From 26 December – 6 January, you can download a gift each day—songs, apps, books, movies, and more—with the 12 Days of Gifts app. Each day's gift will only be available for 24 hours, so download the free app to make sure you don’t miss out. Please note: Not all content is available in all countries.
12 Days of Gifts is a universal app available for free in the App Store. [Direct Link]