Sprint Customer advised not to upgrade to iOS 6.1.1
Submitted by Larry Thacker Jr. on Monday, February 18, 2013.
iOS & iPadOS
I read that some were having battery issues after upgrading and that the problem the upgrade was supposed to fix seemed to be affecting European customers, so I threw out a question to Sprint support about whether I should upgrade my 4S and was advised not to do so. You may want to check with your carrier before performing the upgrade to see if it will get you anything but trouble.
Hi, I did the upgrade last week, and so far haven't had any problems. In fact, my battery might be a touch better than it was. However, if I had read this before upgrading, I would have not done it. Thanks for posting the warning. Cherokee