It’s official, Apple has just released the final version of IOS 9 which is downloaded from compatible iOS devices. This applies to the iPhone, iPad and iPod touch. Go to the settings for setting OTA or so from iTunes by connecting your device to your computer. The update will be offered automatically as usual.
If you have trouble doing the upgrade, it is normal Apple seems to have some problems with its servers. Be patient …
Good news, Apple offers to those on iOS 9 GM the final version – which means no compulsory restoration.
By the way, do not forget to iTunes / iCloud backup of your data just in case.