Also a badly-calibrated monitor can give a very undesirable result color-wise, but a white page should look like your room lighting if we do things right.
Oh and here is a bug that's been niggling at me. If you have your laptop plugged into an external display after the evening light kicks in, then unplug the laptop, it's in screaming bright normal colors on its own screen until you quit and restart f.lux. Same if you plug in the external screen in the evening.
as someone in the "those colors look weird" camp, this might convince me to give it a try. it implies that those i've seen using it have it set up wrong.