Still have an iPhone 4s? iOS 9 is a bitter pill to swallow. Although you can technically download the new operating system if you so desire, you'll miss out on some of the best features and speed improvements on iOS 9. Bumsville.
The 4s is the first phone deemed lucky enough by Apple to survive four generations of operating systems (sorry, iPhones 4 and earlier), which means it can receive bug and security fixes that aren't supported by older versions of iOS. Apple also promised device optimization with iOS 9 to streamline the OS for elder devices following the iOS 8 fiasco in which constant app crashing and horrible battery life rendered many of them practically unusable. After all, there's a giant chasm between the two phrases "it works" and "it works well," and while versions of iOS could work on older devices, it wasn't really meant to.
I decided to experiment: Last night, I downloaded iOS 9 on my old 4s, which I've since forsaken for a shiny iPhone 6. Fortunately, my teeny old 16 GB phone was in luck — you only need 1.3 GB of space to update to iOS 9, a gargantuan difference compared to iOS 8's enormous 4.6 GB space requirement. So, I clicked "Download and Install."
Describing iOS 9, Apple says it's "hardware and software made for each other," but that shouldn't be taken literally when you're still on the iPhone 4s.
The problems start with sheer physics: The iPhone 4s is an anachronism in our big smartphone world — iOS 9 is made for bigger phones. That makes doing most things on the 3.5-inch diagonal display nearly impossible. Want to send a text? Hope you like seeing only one of the previous messages because that keyboard dwarfs the screen. In many apps, all of the text is crammed together, causing a design nightmare.
At first, there was a ray of hope. Opening apps and booting up isn't substantially slower on iOS 9 — which the Wall Street Journal also found in its tests. Compared to the iPhone 6, there is a few-second lag when opening apps and even waiting for some content to download via wifi, especially when mulitasking or taxing the phone's memory. And the new version of multitasking is still beautiful on the 4s, only with a little less speed and fluidity.
But I got a bad case of slowness when it came to the camera app, where speed is key. Capturing an adorable-yet-fleeting cat face (or human face, I guess) requires the app to be ready to go.
That said, Apple's iOS 9 fixes a bug in iOS 8 that makes photo editing a little more 2015. As the WSJ notes, the almost 20 seconds it used to take to look at a photo after snapping it in iOS 8 has now been reduced to around 3 seconds. A small thing, but a nice thing.
Probably the biggest plus for 4s diehards is Low Power mode, which makes it so you can get more use time out of a single charge by sacrificing background refreshing and fewer fancy visual effects. It's helpful for doing a little more Twitter browsing without needing charging cable life support.
With any new hardware comes new features, and of course the four-year-old 4s will be missing a few, like Touch ID and Apple Pay. Not to mention a lack of Airdrop, Handoff and Metal API support. And those cool new iOS 9 tricks like swiping right for Spotlight Search and Siri Suggestions or drawing with Notes? Nope and nope.
So should you install iOS 9 if you're on a 4s? Well, it depends. iOS 7 works really well for the 4s, but Apple and third-party app developers will probably stop supporting it soon to focus on the what's new. If you're on iOS 8, I would say update for the bug fixes, but iOS 7 users should spend some time doing a deep think before clicking "Download and Install."