I've updated both my 5S and Air 2 and wish I wouldn't have. I've already performed backups so I don't feel like rolling back (if they are still being signed).
The exclusion of Home Sharing (music) is upsetting for me because thats a feature I use a lot. It sounds like that is never coming back so waiting for iOS 9 would be pointless, I'd eventually lose that feature.
Also I've encountered few bugs on 8.4 I didnt have with 8.3 such as rotations issues with my Air 2 and my alarm clock not sounding on my 5S. A couple other quarks here and there too like issues with call waiting and conference calls. And Siri asking me to unlock my iPhone to perform a task but not accepting TouchID sometimes.
For a .X update I feel like it introduced more issues then it solved....for me anyway. I'm aware milage will vary.