This is no better than cruise control. I can even argue that it's worse. With cruise control, you know that you have to keep your hands on the road, period. But with FSD, you begin to trust it because most of the time it can work without trouble. It's the unexpected fails that are dangerous, even deadly, as you are traveling at 60+ mph and you are not ready to act.
Tesla needs to release safety data to better understand how useful it is. The fact that it has not, speaks volumes as to its safety and usefulness.