One advantage of starting with the second book in a series is that it often gives you a different perspective. You come at the first book with a greater awareness of the bigger picture, an understanding of the author’s larger scheme. This can, of course, be a disadvantage too as it removes some of the element of surprise.
I’m finding as I read Strangers and Sojourners after Plague Journal I have a greater appreciation for some of the smaller things I might otherwise have paid less attention to on a first reading. The novel is not only the history of a family, but also the geneology of a set of ideas, which then become a way of structuring society. (Or, as Nathaniel Delaney calls it, a plague.) S&S looks to the past, seeking roots, causes while PJ looks to the future, seeking to show effects.
I’m only about a quarter of the way through the book. Will post a review when I’m done. Am finding it hard to put down, though.