Beautifully written and very compelling, though occasionally the descriptions were a bit much for me (why use a plain language when you can use an overly sensual metaphor instead?). I was surprised to learn that the high literacy levels were historically accurate, with most of the Icelandic population being literate since the eighteenth century.
The author notes that historical accounts of Agnes are contradictory and this book's purpose was to tell a more ambiguous version of her story. I'm not sure she achieved that aim. The fictional Agnes and her actions are not at all ambiguous (at least to modern sensibilities); her plight is portrayed very sympathetically. Instead, I read this as exemplifying how women of the time (particularly intelligent ones) were powerless and at the mercy of a hypocritical and unfeeling world, particularly without the protection of a man. Not surprisingly, it was unpleasant. Her life comprised of one unfortunate event after another, poor Agnes has to look out for herself, but ultimately that isn't enough -- in this novel's account, it's mostly the actions of others that, fairly or not, lead to her demise.