With more than 9 million new iPhones sold so far, Apple's iPhone 5S is its most successful ever, and its best challenger to Samsung's Galaxy S4. With all the fanfare over Apple's new hardware, the software sometimes gets short shrift. But not here. Apple's latest mobile operating system -- iOS 7 -- is great-looking, fast and keeps people's most common features much closer at hand. Here's a look at some of the highlights as compared with what came immediately before in iOS 6.