I liked the characterizations and stylizations for the various voices when they each came to the fore. There were two that are almost indistinguishable from each other. I later realized that one had replaced the other, after it was destroy by a cataclysmic event.
What I didn't like
As I said in my overall impression, it can be intensely personal and overwhelming. Perhaps a trigger warning printed on the postcards would suffice to forewarn any audience member.
My overall impression
Shattered is a window into a very personal subject matter that most people deal with, to a certain degree. How do we, each perceive ourselves? What are the dominant voices in our respective subconsciouses telling us? How do we interact with others, accordingly? At times, it becomes uncomfortable to the point where if it was a movie, I know that I would fast-forward past it. In a live performance, there is no such respite.