OK, I found this book both fascinating and annoying. Fascinating because I've always been interested in the great "What ifs" in History and they don't come much greater than the Great War. Annoying for a number of reasons I'll detail soon. Assuming you've read the first book but are yet to read this one I'll attempt to review this without spoiling the story.
The action goes on into late 1916 so we're through nearly half the war by the end of the volume. The storytelling is fascinating, showing the action develop largely from the viewpoint of those who are fighting the war. In keeping with both Turtledove's writing style and the nature of the War, a number of pivotal characters die in this volume and I'm expecting some more to go in the next two. Don't take anyone for granted here. Extra characters are introduced and there are a few cameo appearances from people who fought in the First World War but didn't become famous till WWII. The rebellions in both the USA and CSA are drawn to a close and here it is that I have my first problem. For the CSA deal with their rebellion entirely too sensibly for my tastes. In the USA the Mormons are dealt with the way you'd expect a nation to deal with a rebellion during wartime - viciously and stupidly, the same way we dealt with the Irish Rebellion in 1916. But the CSA seems to come over all sensible and this doesn't really make sense. Why are the CSA behaving better than all the other powers? This is the first problem I have.
The second is with the introduction of Tanks. Having seen Hollywood's latest rewriting of History where an American submarine crew do what the British actually did, having heard that the Americans are about to escape from Colditz in a new Hollywood film, something they never did 60 years ago (but, again, the British did), I suppose I shouldn't be surprised to see the USA inventing Tanks. But I find it unforgivable. Tanks were a British invention, a very secret British invention and the idea that both the USA and Britain could simultaneously develop Tanks... well it's ridiculous. It would have been far better to have had the CSA deploy Tanks in America first, having got them from their British Ally.
That's the main reason I downgraded my review to 3 instead of 4. Also annoying, though acceptable, are the tantalising hints of what is happening in Europe. Italy stays neutral, the Irish Rebellion continues past Easter as the rebels are armed by the USA and the French lose Verdun. The last is the first major indication of how a Western front lacking the Canadians and some British would go different to how it went. On the other hand, the Blockade of Germany still continues and that was crucial in winning the war. Though I complain about this, I find it fascinating and really do want to see what will happen. I will by the next book.