Much recommended, and just a little disappointing. The style--epistolary narrative, stream-of-consciousness reminiscence--does little for me under most circumstances; the only exception I can think to either is Portrait of the Artist as a Young Man, which succeeds in spite of, rather than because of, its technique (Stephen doesn't become an interesting character until he's a teenager; all the moo-cow stuff is silly, at best). The tone is uneven: the main character is well-read and midwestern, but comes off Faulkneresque (I've never been to Iowa, maybe that's how they talk) with digressions of too much technical lucidity.
It is, however, a love-letter to my beloved Reformed tradition, which I appreciated. When I think back on my youth, I mostly remember titanic intelligences who read widely. John Ames is no exception: Calvin and Barth figure prominently. Also Feuerbach and, in passing reference, Sartre; Herbert and Donne. We are literate people, value books, and are not afraid of them, even the ones which are supposedly bad for us--not reading Feuerbach (or anyone else) gives them outsize influence: better to read, understand, and critique. But there is also not idol-worship of any of those figures: we read them for who they are, men who were wise and insightful but still erred.
Of particular interest, in this context, is the discussion Young Boughton starts on the doctrine of predestination. John Ames' response, which is to try to steer around the topic, is the correct one. Most people who bring it up, in my experience, are not interested in having a conversation on theology, no matter how the it is framed: they want to beat up on "Calvinists." The wise Reformed believer avoids the conversation entirely.
The primary theme of the novel is the relationship between parents and children, and I think here it is most radical, and appropriately so. T.S. Eliot's theory of the history of poetry (at one point, anyway) is that each generation reacts to the last in producing its own unique form. So I think it is with the John Ameses. The narrator's father reacts against the radicalism of his father; the narrator reacts against the stern ethical code of his father. Each generation, though, has its own blindness; the grandfather neither saw nor cared about the effect of his radicalism; the father held to his ethics even when it produced a split in the family.
The problem of Young Boughton raises this most particularly: the narrator is so caught up in his story, his way of seeing the world, that he is unable to appreciate Young Boughton for who he is, and see what it is he wants (until it is far too late to help at all). When Young Boughton makes a small request that might make it possible for his life to work out by returning home, all the narrator sees is the impossibility of it. Each generation sees the mistakes of its parents and thinks it has corrected or can correct them. That's all pride.