Only 68 percent of iPhones and iPads are running iOS 8
The latest App Store Distribution data was collected on January 5. Besides iOS 8 data, it shows that 29 percent of devices are still running iOS 7, and 4 percent are still clutching to iOS 6 or earlier for dear life.
Apple's last iOS adoption data was from November 2014, which showed 60 percent of devices had upgraded to iOS 8. An 8 percent uptick in two months time is pretty slow, especially considering the sales boost that Apple must have seen during the holiday season.
We've noted before that iOS 8 has had a particularly rough time getting off the ground compared to older versions of iOS. iOS 8 saw sky-high installs when it first launched--it hit 46 percent of devices just six days after it launched back in September 2014--but then downloads steadily tapered off. By comparison, iOS 7 hit 74 percent of devices just three months after launch, and it quickly became Apple's fastest growing mobile operating system. iOS 8 lost that race.
There are several theories on why iOS 8 installations are lagging. Bugs plagued early releases--remember when iOS 8.0.1 made some iPhone 6 and 6 Plus models basically unusable--and it continues to have little problems here and there, which could contribute to user's hesitation. Many of the perks of iOS 8 can only be accessed on the iPhone 6 and 6 Plus (hello, Apple Pay!), or some older devices might not be equipped to handle the update even if they are technically compatible. (For example, my third-generation iPad is still running iOS 7--it's just about three years old and a little buggy, so I'm worried that an iOS 8 upgrade would significantly slow it down even more. I know I should just ditch it and stick with my iPad Air, but it's nice to keep a relic around.)
Or, it could be the massive size of the install itself: it's about 740MB on the iPhone, and 1.03GB on the iPad. That's enough of a space hog to cause some 16GB iPhone owners to actually sue Apple over the constraints.