For example, you can't set the specific time when you want it to start kicking into effect. When it geolocates itself, it hits full effect by 7pm, which is too early for my schedule (I'm staying with a roommate and optimally want to have it kick in around 9 or 10pm so we can both sleep around the same time).
Additionally, the Mac version only has 4 settings for the color temperature (Tungsten, Halogen, Fluorescent, and Daylight), while the Windows version allows you to manually set the exact temperature you want to set as the "maximum."