My preference is is for blinds to be open. I prefer natural daylight on a day flight. I don't like it when crew get officious and go round telling people to close the blinds.

The only time I will intervene in window blind situations is if sunlight is shining directly onto someone else who is either trying to sleep or work, and will politely ask the person at the window if they would mind pulling it down a little bit to stop the direct sunlight on the other person, I would never tell them to close it completely.