Over the years, I've collected a few iPhone 4's and 4S's, as well as a couple iPad 2's and a new/third generation iPad. They're all equipped with an ambient light sensor that darkens the display in dark settings or brightens it in bright settings. All in all, this has proven to be a boon to me over the years, and made my experiences with the iOS family of devices a generally positive one.
However, I've noticed a consistent problem that still has yet to be addressed on any of them, and it seems like it wouldn't really be much of an issue for Apple to fix: Though it works without a problem (and very quickly) to adapt to the changes from a dark to a light room, none of my newer iOS devices will dim when moving back to a dark room; regardless of how much time I give them. The only fix to this particular issue being to shut off the screen, then turn it back on, which instantly sets it to its auto-dimmed state.
I won't accept that I've somehow managed to accrue a collection of the only iOS devices that have faulty ambient light sensors, and I know that it's not a fault of all of Apple's devices with the sensors (because my iMac, MacBook Air, and MacBook Pro will auto-brighten and dim all day long as the sun shines and then gets covered by clouds, only to emerge triumphant a few minutes later).
So what gives? Is there a fix that I'm missing? Is this a "feature"? If not, why hasn't Apple bothered to fix it?
For the record, this has been on every increment of iOS since 4, (unfortunately) including iOS 6 on the devices I use for development.