Mimicking what it did with iOS 6.0.2, which worked only with the iPhone 5 and iPad mini, Apple has now released iOS 6.1.1 to fix “an issue that could impact cellular performance and reliability for iPhone 4S.” As usual, there were no further details that might give users insight into what precisely the update is aimed at fixing, and whether or not there might be additional fixes involved.
However, several European carriers — most notably Vodafone UK — have recommended that iPhone 4S users avoid updating to iOS 6.1 because of connectivity problems; we presume 6.1.1 is aimed at addressing those issues.
My take: if you have an iPhone 4S with iOS 6.1 and you’re experiencing obvious problems with cellular connectivity, the update is worth risking. In Settings, tap General > Software Update to update over the air, or download and install the update via iTunes. But if you’re not having problems, or if you haven’t yet updated to iOS 6.1, just sit tight with whatever you’re running now and see what shakes out.