Something that's shocking and distressing is devastating. Watching the local ice cream shop burn to the ground would be devastating to many neighborhood kids.
Incredibly destructive events like earthquakes are devastating, although anything that's tragic, even on a personal level, can also be devastating. It's also used informally to mean incredibly affecting or impressive, like a photographer's devastating images of urban poverty. This meaning came into use in the late 1800s — before that, devastating came right from the Latin word devastare, "to lay waste completely."