When I had my Elantra, almost every time I drove it.
My drive to work was at 6 am, drive home was the next day at 8 am, Even on the hottest Houston day, 60 mph with windows down and sunroof open was comfortable in the morning.
Loved cold days, sunroof open, heat on.
It was my first vehicle with one and I used it.
My wife's Santa Fe has a Panoramic sunroof.
We have had it for 5 months, nice cool weather since we have had it. She has opened the sunroof once since we got it, and that was in the driveway when I showed her how to do it.
She does love having the screen open though, as do our teenagers when riding in the back, they say it makes the inside bigger. Now that it is getting warmer, she closes it during mid-day, but opens it (the screen, not the roof) in the morning and evening.
I open it quite often when I drive it (almost every time when by myself).
It is not a must have for a vehicle I buy, but is something I use if I have one.