Barkeepers Friend Cleaner Reviews

I was introduced to Barkeeper's Friend Cleaner about four years ago by a lady that I was visiting. Since then, I have always had it in my house.  It is great for removing rust, grime, etc. 

One of the ways I use it most is in my porcelain sink.  After a while my sink begins to look dingy/dull and marked up by the metal pans and things.  I sprinkle the sink with the Barkeeper's Friend, add a little water to make a light paste, and let it set on for a while.  Then, I scrub the sink with a scouring pad.  When I am finished the sink is bright white and all the "metal looking" scrapes left...