One of the biggest reasons I never apply an OS update from Apple as soon as it is released is because I don’t want to lose functionality.
Sometimes an Apple update just breaks things. This has happened often enough to make me wait until it’s discovered and fixed. But increasingly, Apple has secretly eliminated features or functionality in order gain a financial benefit. It appears this has happened again with the iOS 8.4 release. Home Sharing has been quietly cut from iOS 8.4. If you update, you will no longer have the ability to stream audio from iTunes from your Mac OS X computer to iPhones, iPads, and iPods for free.
Rumors are that such an uproar from the Apple community has convinced Apple to return the feature, but not until iOS 9. So if you don’t want to lose this capability, stay away from iOS 8.4.