Vodafone UK today began sending out text messages to iPhone 4S owners on its network instructing them not to upgrade to iOS 6.1 due to issues with 3G performance. iOS 6.1 was released to the public on January 28.
If you've not already downloaded iOS 6.1 for your iPhone 4s, please hold off for the next version while Apple fixes 3G performance issues. Thanks
The carrier has yet to offer additional information on the issue, but Apple's iOS 6.1.1 update has just entered developer testing earlier this week. Vodafone's message suggests that this update will address the 3G problem, but neither Apple nor Vodafone has explicitly confirmed that this is the case.