The first few chapters were about characters from the previous two books, not about Cash or Reagan. When it finally moves on from that, the bulk of the book is one short step away from dropping the pretense of being a story. It was a compilation of sermons, Bible studies, spiritual Q and A's (replete with proof-texts) to explicate Lori Wick's belief system. I should point out, stories of people's spiritual struggles and revelations can be done very well and be very engaging. This was not that.
The small part of the book actually concerned with the love story between Cash and Reagan really fell short, which is too bad, because Reagan (prior to her conversion) is the most unique character in the trilogy, and Cash is arguably the most marriageable of the brothers. But when Reagan gets saved, she goes from plucky, independent, and savvy to uncertain, naive, and clueless about men. Spiritual brain wipe? She becomes dependent on Cash for literally everything: he's her employer, spiritual mentor, suitor, and she lives in his house. And despite Cash frequently explaining that he's "going slow" with Reagan, extra slow and careful, Reagan goes from being vehemently anti-marriage due to childhood trauma to engaged within 8 weeks of meeting Cash. It took them longer to plan the wedding than to court.
Yet even with all this relational unhealthiness, which I usually devour and enjoy (at least ironically), it was just a dreadfully dull read. The only exciting thing to happen was when Katy broke her hip. The rest is just doing laundry (peacefully, because she's a Christian, now), cooking, and Bible study. Way to end with a fizzle.