I don't know about exceptional case..
I have the 4, don't quote me on the update numbers because they have had so many....
5.1 or something like that messed my battery, 5.2 fixed it, 6.0 messed it again, they gave me a new phone, not before telling me that my phone was off of warranty and there was nothing they would do (even though the update caused battery issues, issues the rep claimed apple were unaware of, REALLY?)
Then comes along 6.1 which I have read nothing but bad reports about and I wouldn't update, 6.1.2 came out and I won't update.. I have an irritating number 1 on my setting app that lets me know there is an update available..I can't get rid of the number unless I update and like that will happen again.. With all these issues I am sure the companies who use to focus on Apple for aftermarket software will start to pay more attention to other phones..
The worst part I find is apples choice not to acknowledge the issues, I feel it shows total disrespect for their supporters.