An excellent conclusion to a great trilogy. Walton never falters throughout the series and her characters remain just as real and enjoyable to read throughout. She has a true gift for making her readers understand how good people can get caught up in their environment and become bad. It's fantastic.
And, of course, part of the reason the books remain readable and not overwhelmingly depressing is that great people rise above their surroundings to do some good.
My one...comment is that the ending seems almost a bit too hopeful. It's, perhaps, a sad statement about human nature that it's more believable that we get worse than better.