I just downloaded OS X Mavericks for my MacBook Pro. I don't know if this is a unique problem, but the screen brightness is automatically adjusting on it's own.
If I set it for about half the bars (50%), I'll be working, then notice that the screen is brighter than normal. I'll check and it'll be at 75% or higher. Then, when I open the MacBook from sleep, sometimes the brightness is at 100% and sometimes it'll be 10%.
What gives? Is there a automatic adjust brightness setting on the new OS that I need to turn off?