i originally thought back up cameras were a waste. but i have to say back cameras are a nice thing to have. they make moving cars in tight confines much easier.

as far as side mirror cameras. i don't want them on my car. something $$$ expensive to break. as others posted. turn you fat head around and look. don't change lanes with just your mirrors and traffic will move much smoother.
in some situations i can see them as good. but in my auto situations no i don't see them as a benefit to me. i don't even want those ridiculous dash screens either. dash screens and camera mirrors probably will a required match.

one downside to me is the brain dead idiots won't hit the side of the garage with their mirror when parking. so i won't get paid to pant, and replace them.