Well I don't have a great response either because I'm in a similar boat. Factory resets and restore from backup seems to be the answer more and more frequently but holy crap that's a pain in the tuchus. Half the threads in this forum have the same stupid response. Restore from backup. Did you restore from backup? You should do that, or try a factory reset. Yeah, that's a great solution. Blow a weekend resetting all my crap. And for your problems, it's the best solution. It sounds like you might have got a bad install or something and I think you just have to bite the bullet. I've had widespread problems before and I hate the big hammer approach but it works. That's my real advice.
I had the iPhone 4 antenna problem, the IOS 6 battery drain issue, the IOS 7 imessage and battery problems, the IOS 8 GMT and wifi issues and now that I upgraded to IOS 9, I'm not sure what awaits. I had to reboot yesterday to get mobile data to work which was disturbing but I'm now just sitting and desperately hoping it's not a trend. I've had an iPhone since the moment I could afford one back in '07 and I'm starting to feel a little abused recently. Remembering the good old days and wondering where they went.
My wife runs flagship level Android phones and as I am her tech support I see all the things she has to deal with too. They aren't better or less frequent than my problems but they aren't worse either. I used to at least be much happier paying my Apple premium knowing my device was more stable with less problems. It's certainly feeling like the only reason I'm staying these days is for...imessage? I'll just go back to regular texting my family.
I used to be the guy who never, ever, ever wanted an non-iphone and now I'm trying to remember why. Habit and routine? The hardware, software and support are all on parity. If I'm going to have all the same problems I could cut my hardware cost in half and get something different and buy a really fabulous dinner with the savings.
