iOS 9’s keyboard has a big change: the alphabetic key caps change case — they’re lowercase when typing lowercase, uppercase when Shift or Caps Lock is engaged. Android and Windows Phone keyboards have always done this.
The good news: You can turn this off and go back to the way the keyboard was meant to be, with all caps alphabetic keys all the time. The confusing part: For some reason, the setting for this is not in Settings: General: Keyboard. Instead, it’s in Settings: General: Accessibility: Keyboard.
Some people love this feature, so it’s great that it’s a setting. I dislike it because having the keys change automatically while I’m looking at the keyboard makes it look like it’s vibrating or flickering. I spent a week with the case-shifting enabled this summer (using the iOS 9 betas) and it drove me nuts. To me it’s distracting and looks a little cheap, and if it were up to me, it wouldn’t be the default.
The main argument I’ve seen in favor of this change holds no water: that this is the solution to iOS 7’s is-it-on-or-is-it-off? Schrödinger’s Shift Key. The proper solution to an ambiguous Shift key is to replace it with an unambiguous Shift key. The lack of case shifting on the keyboard was not a problem on iOS 1-6 because the Shift key on the old keyboard was unambiguous. Whether you prefer a case-shifting keyboard or not, the Shift key should be unambiguous. These are two different things.
The good news is, Apple did improve the Shift key on iOS 9. When not engaged, the arrow glyph on the key cap is now hollow. When Shift is engaged, the key turns white and the arrow is solid black. With Caps Lock on, the arrow gets an underscore.
One more iOS 9 change to the iPhone keyboard: there is now an option not to show the popup character preview as you type (Settings: General: Keyboard: Character Preview). The iPad keyboard has never shown these previews, presumably because the keys are big enough that you can see the keys themselves highlight as you tap them. Prior to iOS 9, however, the iPhone keyboard has always shown them.
While running beta versions of iOS 9 over the summer, I tried turning off character previews, but soon turned them back on. I’m just too accustomed to them after eight years of daily iPhone use. With previews off, it feels to me like the keyboard isn’t working.
[Update: At one point during the summer, the iOS 9 betas were defaulting to not show character previews, and I incorrectly assumed this was still the case when I first published this piece. In the release version of iOS 9.0, characters previews remain on by default, and I’ve rewritten the above accordingly. Sorry for any confusion.]