Apple iOS 7 is the latest version of the mobile operating system for recent Apple devices. It's now available for download and installation on the iPhone 4 and later, 5th generation iPod Touch and later, and iPad 2 and later. Obviously, some hardware-dependent items and features such as the fingerprint scanner will only be available on the iPhone 5S. As with any substantial OS upgrade, it may be prudent to proceed with caution for several reasons.
- Be aware it's visually quite different, and some things have changed. See this side-by-side comparison between iOS 6 and iOS 7
- Some existing apps may not work, at least at first
- There will be some bugs (not because it's Apple, because it's inevitable)
- If you have a company phone, you should probably check with IT first - they may not be ready/willing to support iOS 7 fully yet