We have had a few pieces fall off, however, I thought that it was a problem with the installers, not the stone itself. We just glued the pieces back on the construction adhesive and haven't had any more problems. Ours is about 13 years old.

So it doesn't collect moisture in the cracks or problems with insects getting?

I live in SoCal, not a lot of moisture here. Spiders love it.

Dry stack stone is a much better fit for the interior, it does seem to fall off on the exterior quite often, either moister, or the piece of stone was did not have enough mortar on it, and most common is the stone itself has not been properly cleaned by the producer, causing it not to stick an oily substance they use on the molds I would say 75% of the time it's the Manufacturer

You are much better off using mortar between the joints if you can stand it, it puts every stone to a bond with each other