I don't know if Irving has any more children's books in him -- I certainly hope so. This one is an excellent first effort, and anyone familiar with his novel "A Widow for One Year" already knows the story.
My three-year-old son sees and hears ghosts and monsters everywhere. He's not afraid of them; they're just there, part of his nighttime world. This book is right up his alley, full of spooky speculations about what might be, and even when the simple explanation comes out, why, that just might be scary too. This is far more interesting to my son than if everything had just been hunky-dory A-OK. In a moment this became his favorite book.
I'm a huge Irving fan, and I'm delighted that I can now share his work with my sons before they turn 18.