Apple flaunts the high adoption rates for the latest version of its mobile operating system every year, but the truth is, year after year, iOS users grow more wary of software updates. In the latest figure published by mobile analytics firm Mixpanel, only 11 percent of users updated to iOS 9 in the first 24 hours.

That is a drop of three percent over last year's figures for iOS 8, and it's five percent lower than rates for iOS 7. Users are starting to become more cautious of Apple's updates, after the botched iOS 8 launch was plagued with issues.

Related: Apple iOS 9 review

Even so, the iOS adoption rate is still much higher than Windows or Android adoption rates, and 11 percent amounts to millions of iPhone and iPad users. All of Apple's most popular devices are compatible with iOS 9, so it takes less time for users to upgrade to the new version of iOS than it does their Android and Windows counterparts. For Google and Microsoft, it is a challenge trying to get manufacturers to push the updates to devices on time, so the delay is understandable, albeit irritating.

Even though iOS 9 is behind iOS 8 right now, mobile intelligence group Crittercism claims that the new update will reach 50 percent before iOS 8 hit that number. The platform found crash rates on iOS 9 were one percent lower than iOS 8, which could lead to more updates in the next few weeks.

Related: Check out Apple’s News app — It’s great

Apple's iOS 9 did suffer from server issues in the first hours, with plenty of users receiving a 'Software Update Failed' message when trying to download the update. Not all users were affected, and Apple fixed the issue a few hours after launch.

Apple has not released any official figures for iOS 9. We expect to hear an update in the next few weeks.

iOS 9 brings a load of new features to the smartphone and tablet, including a new search panel, updated Siri, transit maps, multi-tasking features for iPad, improved security, and more battery life. News, Wallet, iCloud Drive, updated Notes, and an updated keyboard all come in the new OS as well. However, Apple has lowered the size of the over-the-air update by three quarters.

There is still anger amongst iPhone and iPad users that they cannot remove permanent apps, but Apple's CEO Tim Cook said he was open to the idea of removing some apps that aren't connected to other services inside iOS. The ability to remove preinstalled apps will not be available on iOS 9, however.