iTunes users who rely on Home Sharing to stream their songs to other networked devices may want to hold off on iOS 8.4.
As several users in Apple's forums have pointed out, the latest version of iOS doesn't support Home Sharing for music. That means if you've got a bunch of songs stored on your Mac, you can't stream them over Wi-Fi to your iPhone, iPod Touch, or iPad for the time being without turning to third-party solutions. Home Sharing for music does remain available to Apple TV users, at least, and video sharing should still work on all devices.
The reasons for the removal are unclear, though 9to5Mac speculates that licensing agreements for Apple Music could be to blame. The new streaming music service is limited to one device per iTunes account at a time, so Apple may need to ensure that Home Sharing doesn't function as a workaround. The release notes for iOS SDK 8.4 do list the unavailability of Home Sharing as a known issue, so there's hope that Apple is working on a fix.
Why this matters: For some users, iTunes Match and iCloud Music Library may obviate the need for Home Sharing, as both services upload your music (or match known songs with iTunes versions) for streaming from anywhere. But while Home Sharing is completely free, iTunes Match costs $25 per year, and iCloud Music Library is a feature of Apple Music's $10 per month streaming service. If you're not keen on more subscription fees, it's best to hold off on iOS 8.4 or try an alternative prgram for local streaming.