Used this product on a fireplace exterior chase.  Was easy to use and install.  Follow directions and think about what you are doing and the average DIY (like me) can get good results.  The look of the finished project enhances the house and looks like real stacked stone.  Time will tell on durability but seems robust.  One suggestion to GenStone is to make 1' filler pieces to cut down on install labor for cutting small fillers when the project requires.