Window tint can give you many benefits: 

The first is energy efficiency.  Heat energy is reflected back.  In the summer time, most external heat or the sun's energy is reflected back out the window, and will save on the amount of usage of air conditioning.  In the winter time, window tinting reflects the heat energy created by your furnace back into you home.  So window tinting actually saves you money in energy usage.

The second is Fade resistance.  Window tinting rejects 99% of the ultraviolet rays that can damage your floors, carpeting, furniture and other things.  Window tinting saves you money by not allowing the sun to destroy your home from the inside.

The next benefit is privacy without closing your blinds.  Nothing would be worse than to close off your view of nature.  Tint allows you to keep the view without closing off the great outdoors.  Depending on how dark or reflective you go, it may allow you to see animals or people outside your window without them seeing you.