Comment by jerlam

It's fine for a passenger, especially in the back seat. But as a driver, it adds a potentially bright source of light right at the top of your vision, and that can be annoying as hell. I covered my roof and I felt more relaxed since my eyes didn't have to adjust if I accidentally looked too far upwards.

Indoors, we avoid lighting a room with single bright overhead source of light. But this glass roof fad adds it to cars.