One of the benefits of painstaking accuracy in historical fiction is the richness of the imagery that makes the reader feel there. One of the risks of painstaking accuracy in historical fiction is that the interest level of the plot may suffer in sacrifice to that accuracy.
Dr. Gabaldon's Drums of Autumn is big and sweeping enough to provide ample examples of both the benefit and the risk. Despite its size and scope, I don't have a lot more to say about it.
One downside of this large multi-volume saga, now that I'm four volumes in, is that I'm having trouble remembering what happened in which of the volumes. What, you mean I need to have my copy handy in order to review it, or risk moaning about a sub-optimal plot point that actually happens in Voyager? Do tell!