Character is a strange subject for this story. The 1st-person protagonist has very little personality, but I found myself not caring. The other "main character" in the story was far more interesting. While no character had a true arc, what we saw of him arced somewhat from the beginning to the end (that is, if the twist ending was really a twist ending...) Characters are definitely not this story's strong suit, yet for some reason it felt fine anyway.
The setting of this story is really cool. It's set on Earth around 150 or so years in the future, perhaps a little further. The speculative element of it (we really are alone in the universe) is kinda unique for a sci-fi story and allows for the conflict to be bold for readers.
Plot acts as a stock car for this story. It's a metal cage with little adornment, except an advertisement (wow, my metaphor is even funnier than I originally thought because there's an advertisement occupying space in the middle). The last twenty-five percent of the story is where the money lies. I already mentioned the twist ending that may or may not be a twist ending (you have to read the story to understand).
This is not my favorite story by any stretch, but it isn't bad, especially not for a story of its length (around 2,000 words I'd estimate). If I notice any stories by Jack McDevitt in future issues of the magazines I subscribe to I'll certainly take the time to read them.