

This post has been updated.
Apple $AAPL is scheduled to release iOS 9, its latest operating system for the iPhone, iPad, and iPod touch today. It is a free update, and anyone with an iPhone 4S or newer will be able to upgrade.
What’s different?
When you swipe right from the iPhone home screen, you’ll find a new universal search dashboard, where searches will scan your iPhone, email, inside apps, maps, the web, sports scores, your photo library, and more, and will even be able to perform simple math calculations.

A big factor in iOS 9 is that Apple is trying to be more proactive with its recommendations. So this screen will also contain links to things Apple thinks you will want to access: Top contacts, new or relevant apps, local information, and news, contextually tailored.
As Zach Seward wrote earlier this year, iOS 9 includes several improvements for messaging apps:

Apple is discontinuing its Newsstand feature in iOS 9. This means that many news apps—such as the New York Times, New Yorker, and many other newspaper and magazine apps—will just be normal apps again.
Apple is launching (and pre-installing) its own News app in iOS 9, where you’ll be able to subscribe to and read free stories from a variety of publications, including Quartz.

iOS 9 isn’t a dramatic visual change from iOS 8. But Apple has changed the system font to a custom typeface called San Francisco, instead of Helvetica, which it had used since the beginning of iOS. People seem to like it so far. (It’s the same font as the Apple Watch.)
Apple said in June that its under-the-hood improvements can add about an extra hour of real-world use per charge. It’s also adding something called “Low Power Mode,” which it said can extend battery life an additional three hours.
Yes. Unless something unexpected happens and there are major roll-out problems, iOS 9 will likely make your iPhone run better, not worse.