It's magic. NOT! The ambient light sensor is where the LED is on the front of the BB. The reaction is not very quick, but it's pretty quick. It takes a few seconds for it to react, but it works. Sometimes it's a little anoying.
I actually love the sensor, allows me to never have to adjust a backlight of any kind and is always set perfectly. I think it works pretty well personally.
Posted from my CrackBerry at wapforums.crackberry.com
at times it gets really irritating when u actually need the screen light but the sensor makes sure the brightness goes off in a bright place, is there anyway we can switch the sensor on or off ?