I was going into my basement earlier (where the game room is) and I dropped my core Rulebook down the stairs as I was turning the light on. There doesn't appear to be any major damage. Just some minor damage at the edges of the cover. The iPad was dropped too but it wasn't damaged.
I guess if the book gets too beat up then I will just get a new one and let the kids have the old one.
BTW: If I had a PDF of the book then the hardcover one would never have left the game room. :-)