I didn't buy these for light blocking, and they really don't block much light.  I bought them because the price was right and the color was right.  These curtains hold on to wrinkles.  I followed the directions for removing wrinkles but they are still kind of a mess.  Also, i bought 4 panels, and when light shines through them, 2 of them seem to be a different color than the other 2.  This only happens when light is shining through and the curtains are closed.  Otherwise, they all appear to be the same color.  But the biggest thing is the wrinkles and creases.....  makes them look a bit messy.