You might think it's too early to draw conclusions, but the last time I did this a good chunk of the people who wanted a copy jumped on the offer the minute it went up.
So, I think there's one (or both!) of two things going on:
1. The audience is pretty much the same as it was six months ago. I though there might be some churn there and that some people who didn't want the book before would want it now that it has positive reviews, but it doesn't look like it
2. The cover is a generic default cover. Other books also have generic covers (or no covers at all--they're having cover trouble over there); overall those books do seem to have lower levels of sign-on.
What does this mean?
Well, given my suspicions about #2, I should continue to hold off on a Goodreads giveaway until Goodreads decides that it is, indeed, physically possible to correct the cover art.
But #1 means that I need to start branching out instead of trying repeatedly to tap a well that has evidently run dry. And given the lack of interest in a free sci-fi book on Kindleboards, I really need to start looking at sci-fi oriented Web sites.
You know, the nice thing about using giveaways is that you're basically conducting marketing experiments without having to pay for advertising. It's a good way to test the waters.
Anyway, obviously it's going to take time, effort and thought to figure out where to market, and I'm wondering if I want to bother with that before I make Trang free. It seems to me that advertising is just going to work better with a free book (especially if people don't have to go to one specific retailer, register, and enter a coupon code). So for now I'll focus on finishing the large-print edition and writing Trials (not to mention family stuff--I've got a lot of trips/houseguests coming up); marketing-wise I'll just focus on sci-fi cons (I may have some interesting news on that front in a little bit), then enroll Trang in KDP Select, and then make Trang free and worry about ads.
I should note that a major motivation for having a giveaway and chat on Library Thing is simply to ensure that the people who read and liked Trang from the first giveaway know that Trust exists. This, obviously, is worth doing, and worth doing every time a new book in the series comes out. I'm just not going to be finding a lot of new readers this way.