Well, F&SF doesn't want it. Fast turnaround, I'll give them that.
I'm not sure where to go from here. I've shown it to about a dozen or so of my friends so far, of whom two have read it, and the only editor to touch it rejected it without useful comment. This is not exactly a stellar record for something that I'm hoping that thousands of people will read and enjoy. All the advice at this stage is to put it back in an envelope and send it on to the next market, but that's under the assumption that there are plenty of markets for the work, and there aren't.
I think the plan will be to do another round of revisions, and maybe look into an online workshop like Critters. I think that it needs to be shorter before I attempt to send it to Analog, which I think is the next stop for this beast.
Edit: One point that needs clarification: First, I am NOT, NOT, NOT unhappy with any of the people who got copies and didn't read it or didn't comment: the whole point of the exercise was to see whether people would pick it up, read it, and like it. 2/10 is a datapoint, not a disappointment. (Well, it's a disappointment, but in the story, not in the readers)