It could have been wonderful. The idea of addressing the juxtaposition of the American immigrant experience with World War I was intriguing. There is a lot of potential here. Unfortunately, the plot was merely okay and the character development was weak. Knowing who will end up together is not the problem - we often have romance novels figured out. But the road to romance is so poorly written I don't think I would have finished the book were it not for the recommendation of a friend and the promise of a twist ending.
Lang is simply too verbose in all the wrong places. The classic example for me was the following. The setting is: smitten agent seeks disappeared love interest. he runs to the office where she was last seen to find out the door is locked. Lang spends an entire paragraph delving into his past and telling us how he learned to pick locks (and it goes back to his relationship with his father). What?! While this flaw could have been solved with better editing, all the missteps of this work are not so easily remedied.
As for character development, we are informed REPEATEDLY in the opening pages that our hero, David de Serre is a man of few words, yet he suddenly becomes eloquence perfected when he encounters our heroine? Where is the confusion generated in her (or others) by his reticence? How does this make him a good agent? etc. While time is given to the three major characters of De Serre, Liesel and Josef, the parents and siblings are rather blah, begging to be drawn more vividly. Rather than merely state that the two fathers raised their sons differently, it would have been better to see some concrete examples of the difference in home life/ activities/ memories of our coming of age young people (although they are really a bit old for their parts here). The death of Josef's mother is mentioned, but never explored in regard to his relationship with his father. The immigrant struggle and experience of the parents is not explored beyond factual details. And the experience of second generation immigration is trivialized - Josef wants to be German, Liesel wants to be American. We know this because they state it several times, and the report on each uncovers that Liesel only participated in American clubs growing up and Josef in German ones. If the immigrant experience were this tidy it wouldn't be a source of story!
Finally, it takes more to write good historical fiction than a knowledge of what year the Lincoln Memorial was built. While modern sensibilities are not quite projected onto our characters, they really have no cultural grounding, leaving them flat. The one area that is filled out is the romance genres use of "words as a caress" and reference to the cardiac state of the intendeds, etc. In addition, the repeated, and highly inappropriate for the time, scenes of physical contact between our heroes only serves to obliterate any tension built by the plot. Rather than shocking the characters into changing their actions (as would have been required in the setting) they merely plod on, sharing their boring 'wonderings' with us. blah. blah. blah.
But perhaps the character least served by this lack of setting is Josef. I am not familiar with the tone of German Americans during the first World War (that was something I wanted to learn about), but much of Josef's impetus for his actions seems to be a Nazi-ism that wasn't present in this time period. There also seems to be a thorough knowledge of Darwin's "Origin of Species" which I find to be strange, given that the Scopes trial thrusting Darwin into school curricula across the country took place 7 years AFTER our setting (and keep in mind that the Scopes trial opened the teaching of evolution to COLLEGES - and only one of our characters attended college). Placing these ideas into Josef's character in such a developed form is ridiculous for a young man coming of age during the World War I.
Finally, Christian readers will find a real theological problem in the articulation of differing perspectives. "America is a nation blessed by God." is set up against "the rightful ascent of German ways". And I cannot understand the scene from which Liesel determines "Josef loves Germany more than GOD!" Oh my! The patriotism and nationalism of our time is a subject worthy to be examined, but Lang's presentation comes as racist (Germans are the enemy in the war, so we are supposed to dislike them), sectarian (protestant Americans are better, wiser, and just plain right compared to those Germans we are supposed to dislike), and without Biblical foundation (if God can acknowledge the pagan practices of the Babylonians, yet use them as part of His plan to discipline Israel, I think it is quite difficult to assert that God is on a particular side in a modern war). How theology played out in the experience of German Americans would have been another wonderful theme to explore, but alas, we shall have to look for other works to do so.
World War II has generally overshadowed World War I in fiction, but Bodie Thoene has an excellent series called "Shiloh Legacy" that starts with "In my Father's House". Those looking for good historical fiction would do well to read anything by Bodie Thoene or Lynn Austin. Lynn Austin, though she doesn't cover World War I, creates excellent work in historical settings. I particularly enjoyed her Civil War series which starts with "Candle in the Darkness" - i have yet to be disappointed in a Lynn Austin novel.