Many 4S's suffer from a very sensitive front facing camera. It can be incredibly sensitive to rapid changes in light/dark causing it to flicker, freeze, and often crash. However I have noticed that since the update its more solid. It still flickers with rapid light/dark changes but no longer freezes or crashes. Plus it has face detection which was only on the rear camera previously. If you were having the camera issue have you noticed your camera is now more stable?