I always update through iTines and rarely have any trouble. I would bet most people who are having trouble do not update with iTunes.
Not a surprising question coming from someone with a 64GB iPhone. At least for me, doing the install OTA required at least 4.2GB of free disk space which I do not have and I refuse to get a higher capacity iPhone just so I can update the software via OTA.I only update through iTunes now if I have to restore my phone for some reason. Why do it when OTA works just fine?
I did an "upgrade" on my iPhone 5s from iOS 7.1.2 via iTunes using the iOS 8.0 GM release back on September 9th and haven't had any performance or battery issues.
I do a restore through iTunes for every mayor release. Set up as new phone and no backup, of course.
What do you do about your contacts? Do you restore them via icloud?