Three Farmers is quite a bit like the later Powers novels I have read in being contrapuntally structured, with three distinct narrative lines that begin by seeming unrelated, then intertwine and approach each other without quite meeting throughout the book, finally to resolve and reconcile in the end. (The other novels of his I've read have two lines, not three, but to the same effect.) It is like the others too in being markedly cerebral, grappling large ideas and encompassing wide reading, in this instance about the history of photography and the era of World War I.
It's also unlike his later novels in some ways -- one, the narrative voice sounds like a wise-ass rather too often. Had I read the book when it was published, in 1985, when I was 31, I probably would have enjoyed this tone more -- well, my loss. The other difference is that none of the female characters in the novel seems even close to real. Couple of salty gals, junior and senior divisions (Wies/Mrs. Scheck), a too-good-to-be-true sweetheart (Alison Stark), an ethereal, touched-with-divine-madness artist, but none of them seem quite plausible. Compared to Laura in Gain and Karin in The Echo Maker, two unforgettable female Powers characters, the women in this book seem almost not even there.
Amazing book all the same, though. The sense of historical change and our occluded but real connection to the past were what he was really going for, I suspect, and those things are wholly there. I have yet to read a Powers novel I wouldn't recommend highly.