it sure helps a lot, but not fool proof
taking the faceplate off becomes a pain in the ass when done routinelly, espcially if im going to the grocery store for like only 15mins. If my car is parked in a ghetto area, i take my face plate off, otherwise i just flip it over(i dont think this works, thieves arent that dumb, you can easily tell the diff. between a flipped over stereo and just a blank compartment, but im just doing it for the sake of false sense of security)
im thinking of getting some reflective tinted window, but doubt that will work well, since you can look through it when you stick your eyes right on the glass.