I am coming from a 2008 aluminum MacBook which I bought on day zero. The automatic screen brightness on it works perfectly. When I am in a dark room, the brightness goes down significantly, so I am not blinded. When I am in a bright room, the brightness goes up. The keyboard backlighting was equally consistent and worked great. I now have a 2012 Air and the automatic brightness doesn't seem to work as well. Specifically, it seems far too bright in a dark room. I use it in a pitch black room and the brightness goes down a bit, but no where near as low as on my MacBook. I have to manually turn it down further. I never notice the keyboard backlight change. It also never seems to turn off, even when I am in direct sunlight. This is how it worked on my MacBook. I know the sensor is working, at least partly, because if I am in a bright room, I can cover the sensor with my finger and the screen dims a little. Is this the expected behaviour? Does the keyboard backlighting never turn off automatically? Is your screen dimming enough in the dark? I literally never, ever, had the need to manual adjust my screen or keyboard brightness on my MacBook.