My boat, bought used in 1998, came with tinted windows done professionally: lightly tinted on the front, heavily (limo) tinted on the side and to the rear.
I've never regretted having them tinted, and they do afford a useful amount of privacy, although at night a well lighted interior is still quite visible from the outside.
The darkening is very restful on a bright sunlit day, and I would do it again if I were to puirchase a new boat. I like iot a lot!
One might think that the tinting plastic material would scratch easily, but I'm careful when washing the window interiors where the tinted material lies.
If you do it, try a window or two to see how you do, getting an exact fit and eliminating bubbles are harder than most folks imagine. I did it on one window that had to be replaced, and would have it professionally done if installing tinting on all windows at once.
Joe.