The auto brightness settings don't work so well on these so-called "smart" phones.
Why Auto-Brightness on iPhone, Android is Awful : Read more
Why Auto-Brightness on iPhone, Android is Awful : Read more
Bug or not, not good, and not appreciated by many. yet another something apple should do something about, but probably won't and instead if complaints come in apple will say: "Your looking at it wrong!"It actually does dim the screen again, it just takes it a minute. Not sure if it's intentional or a bug though. If it's really bothering you, locking and unlocking the phone quickly will set the screen's brightness relative to the ambient light.