Apple's latest iOS distribution figures show that nearly half the world's iPhone and iPad users moved to iOS 8 within four days of its release.
Apple only released iOS 8 on 17 September, but according to its latest figures, 46 percent of devices that visited the App Store on Sunday 21 September were running iOS 8, while 49 percent remained on iOS 7 and five percent were on an earlier version.
The numbers also contrast with several reports last week, noting takeup of iOS 8 was much slower than iOS 7 during the first 24 hours of availability.
Ad network Chikita reported iOS 8 adoption within the first 24 hours at seven percent compared to iOS 7, which reached 18.2 percent in the same timeframe. Tapjoy similarly found a slower response to iOS 8.
A number of things could have contributed to the slower immediate take up, including that the installation required around 5GB of space to download over-the-air — though connecting the device to a computer bypassed this constraint.
And while iOS 8 is compatible with the iPhone 6, iPhone 5S, iPhone 5C, iPhone 5 and iPhone 4S, the oldest device on that list isn't really cut out for all iOS 8 features. For example, it's missing TouchID, while iOS 8's larger screen optimisation doesn't benefit the 3.5-inch display of the iPhone 4S.
If iPhone 4S users stick to iOS 7, Chikita estimated that only 65 percent of the pre-iPhone 6 North American iPhone user base would be in the market to adopt iOS 8. On the other hand, there are already the 10 million and counting iPhone 6 owners and that may help break iOS 7's two month milestone of 74 percent.
One potentially concerning figure for developers though, as 9to5Mac points out, is that Apple's review process for App Store submissions appears to be backlogged. Apple's figures show that 74 percent of app updates and 53 percent of new apps are being reviewed, compared to the usual 90 percent range that's still happening for apps for Mac OS X.