Umm, eww. That was one of the more prevailing thoughts as I read this short story. To say the least, the images invoked by the descriptions were vivid, verging on gruesome. And since that definitely seemed to be the tone the author wanted - as it fit the story - it was well done. I feel that I should add that there isn't really gratuitous gore, by any means, lest this paragraph conjure that thought.
As usual, I'm less a fan of short stories because there is much less time for characters to develop or be fleshed out. Still, even in such a short time, the author established some solid characters that felt consistent and realistic throughout the story.
One thing that might be less than perfect was conveying Shaun's paranoia. It seemed like the author was trying to do this, yet even towards the end I didn't sympathize with Shaun's actions as much as might be hoped for. Hmm, that sounds really dumb/doesn't make sense, but I don't know how to explain what I mean without saying what happens, which I try to avoid doing in my reviews.
The ending, in retrospect, was really super obvious. Yet I didn't see it coming at the time. Well done on that.
If you don't mind a bit of gruesome description; I'd recommend this short story.