[toddos]

Ouch. It breaks color management profiles. Every LCD screen, deskktop or laptop, generally has massive blue shift. Everything is overly blue, with reds and greens washed out. You can fix this by either calibrating your monitor (expensive, time-consuming, but the best option) or finding an icc profile from someone with a similar monitor who's already calibrated and using that. However f.lux resets back to the monitor's default. That's awful.

Edit: I tried the Windows version. According to the "recent updates", the OS X version actually respects color profiles. The Windows version quite obviously does not. So maybe this would be decent on a Mac, but it's unusable under Windows.