Curious. I have a 5c iPhone and an iPad 2 and neither has suffered more than about 10% change of battery life under iOS 8. Your unhappy experiences may be related to other additional causes than strictly the version upgrade.
I don't think so because if you go to the Apple forums there are many, many people who have had the same experience. If one contacts Apple their "fix" it to upgrade the product. Sorry, but I am old school and believe a product costing $500 should perform more than 3 or 4 years.
Well, I just got the update and will see what it does while at work tonight-tomorrow. I’ll report on this thread tomorrow morning.