Well, good question bandito. I wish when I bought our car I got one with tinted windows in the first place, as even though the car was second hand, there were loads of models on offer (but we got ours from family).
The shades are well made and plenty above seem happy with them. I am just trying to sort fixing mine in place properly, but they do add to privacy, shade the car loads and look better than the stick on shades with mickey mouse etc on. They are also designed for each model, so look neat when in place.
If I bought another car, I would make sure I had the tinted widows option (just think it makes sense to keep the cabin as cool as possible, helps keep sun out of kids eyes etc). Also was helpful when I had my Nissan Juke – could just leave my bike on the back seat and it looked very unobtrusive.