The best parts of this book were the period details, which mostly came through fine except for the occasional anachronism or linguistic infelicity. The texture and tenor of early Cambridge and the attempts to Christianize the local native societies (with the concomitant tensions) came through well. The rest of the plot seemed just a bit unlikely, and using Bethia's "journal" as a framing device didn't work quite as well as it might have done.
Entirely worth reading overall, even if not quite to the level of Brooks' Year of Wonders (still my favorite of her novels).