That is actually not as good as it sounds. Your body cannot twist a full 180 degrees, so while you can see right behind you and out the passenger side, anything coming from the drivers side is not possible to see.
It takes some getting used to, but once you learn to back via mirrors you won't want to twist around anymore. You do need to check behind the car beforehand because you cannot see directly behind you and thus might hit something on the ground. However you get much better visibility to things that are moving from the side to behind you, and that in my experience is where the danger is most of the time.
I do favor backup cameras though. They show you things you would miss either twisting to look backwards, or looking in the mirror.
It takes some getting used to, but once you learn to back via mirrors you won't want to twist around anymore. You do need to check behind the car beforehand because you cannot see directly behind you and thus might hit something on the ground. However you get much better visibility to things that are moving from the side to behind you, and that in my experience is where the danger is most of the time.
I do favor backup cameras though. They show you things you would miss either twisting to look backwards, or looking in the mirror.