Apple released a free iBooks title on Friday, iPhone User Guide for iOS 6. As the name suggests, it's a user guide for iPhone 5, iPhone 4S, and iPhone 4 that is specific to iOS 6, which was released on September 19th.
The book's description:
Here's everything you need to know about iPhone, in a handy eBook format. Get to know iPhone and discover all the amazing things it can do, and how to do them. It's the definitive guide for getting the most from your new iPhone, straight from Apple. The iPhone User Guide is an essential part of any iPhone library.
Screenshot from iPhone User Guide for iOS 6
Topics include a list of status icons, working with iCloud, how to sync with iTunes, gestures, and individual sections for each of Apple's built-in apps.
All told, it clocks in at 296 pages, and it will be especially helpful for those who are new to iOS or simply want to know more about how it works.