This is a very short, one-room game. It's essentially the IF equivalent of a pun - even if you do manage to figure out the single puzzle, you'll end up groaning rather than laughing. If you like that sort of joke, you'll like this.
I really liked this one. The juxtaposition of the two storylines, the non-linear time progression, the use of different voices — all excellent.
The main story is a moving one; but the moment that I felt was the strongest, in the sense that it made me stop and go "oh wow, oh wow, oh wow", actually occurred in the story-within-a-story. It was a small thing, but it really got across one of the reasons why I should care deeply about the main character.
To give some context here, the main attraction of IF for me is the storytelling - I enjoy the odd puzzle, but not half as much as a well-told story. The storyline of Shrapnel is interesting but not ground-breaking; Shrapnel's strength lies in its medium. The choice of IF over paper and ink pulled me forcefully into a narrative that I might normally have dismissed as "not my thing". Moreover, it's a story that I plan to read again, or at least skim.