Bothari does make for an interesting sociopath, more sympathetic than such characters are usually drawn. It's hard to tell how much of that is just Bothari, and how much is a reaction to the abuse he suffered at the hands of Ges. One of the most striking moments, for me, is actually back in "Barrayar", when he's playing the thug in the brothel, how naturally he slips into that role and, in some way, seems more like "himself" than we've ever seen him before. Like every other role is just a role, but this is the "real" Bothari. It was chilling, to see a mostly-sympathetic character turn on a dime like that. I don't know that I'll ever think of him as a favorite character, but he's definitely interesting.

In terms of how thought out things have been, I was thinking mostly in terms of specifics of backstory. The most memorable example, for me, was during the trial, during which Gregor selects the Vor whose son is responsible for Miles's disability as one of the witnesses. Bujold is pretty detailed about the fates of the sons, so either she wrote that in offhand and had to make it work in "Barrayar", or she had already scripted that part of Barrayar out. I think I may have to re-read the Afterword of "Cordelia's Honor" after I finish this volume; I recall that she went into detail about a few things like that, and I imagine they will make more sense knowing more context.