If you've run into problems with the auto-brightness settings on iOS where your screen isn't adjusting properly (or at all), then you know how incredibly annoying it is. Tech blog Addictive Tips shows how to fix this with a simple recalibration.
Essentially, in iOS 6 the way auto-brightness works was tweaked slightly to work better, but the downside is that it's easy to make dysfunction if it's not set properly. For example, my iPad seemed to crank up the brightness every time I was in a dark room. That's the exact opposite of what I wanted.
To fix it, you need to head into the brightness settings (Settings > Brightness & Wallpaper), toggle auto-brightness off, and then adjust the brightness slider to the minimum setting when you're in a dark room. Next, toggle the auto-brightness setting back to "on," and it should be calibrated and working properly. If that doesn't work, you can try calibrating both the maximum and minimum levels. This seemed to help with my problem at least, so if you're having trouble with auto-brightness it's worth a shot.
Fix iOS 6 Auto-Brightness Issues By Calibrating iPhone Light Sensors | Addictive Tips