After updating my iPhone 3GS to iOS 5.0.1, my phone started showing signs of something not sitting quite right with it's newly installed software. The phone became slow to respond and it would shut down and would not restart until plugged into a charger even though the battery level would be anywhere from 15% to 70%.
I booked the phone into my local Apple Store to talk to the Genius Bar and was told that there may have been an issue during the upgrade and they offered to wipe the phone and do a clean install of the iOS. We set the phone up as a new phone and gave it a try but the same issues existed.
I took the phone back to the Genius Bar and was told that perhaps making sure that all apps that weren't needed were shut down to minimize the demands on the phone. Unfortunately that didn't help either (I make sure no more than 4 apps are active at any time).
I returned to the store a third time, just as a walk-in, and was told the phone should be replaced, even though the diagnostics showed no issues with it and it's less than 2 years old. Another solution would be to upgrade to a new iPhone 4/4s.
When I mentioned that the problems all arrived with the upgrade and suggested that they downgrade the phone back to iOS 4, I was told that once the firmware had been upgraded there was no going back.
I tried calling Apple support to complain that the upgrade has made my phone very frustrating to use, but the automated phone service directed me to a request to purchase AppleCare before I could even discuss the issues with anyone.
As someone who has owned and sung the praises of Apple products for more than 20 years I find it disappointing that issues arising from "upgrades" cannot be resolved easily and are undoable.