My wife and I had two very different problems upgrading our iPhone 4 to the new operating system. My download and install took multiple hours. My wife's install was faster and then the screen locked up and iTunes demanded a backup password. After two hours of multiple attempts and Google searches, we ended up losing all her data in order to turn her brick back into a phone.
Do we like the new features of the iOS 5; I especially like the pull down menu and info on the locked screen. But I am experiencing a significant drain to my battery life. By the time night time approaches, the battery is at 5%. That is 15% lower than what I normally see on a typical day of usage. Last night, I deleted my iCloud account just to see if that would result in an improved battery life. It reinforces that the next notable improvement in technology must be a quantum improvement in battery life.
Will this stumbling block with iOS 5 upgrades hurt Apple? The bells and whistles resulting from the upgrade are great. Apple should respond and correct these installation issues ASAP. Regardless, customers are still looking forward; to the release of the iPhone 5 and iPad 3.