This second series taking place soon after Turtledove's well received "WorldWar" saga is a good read that kept me entertained. But it is also a disappointment in that it's pretty clear that the author padded the book enough so that he can make what could probably be written in 2 books into a 4 book story.
What's particularly unfortunate is that Turtledove pads the book with largely irrelevant character building that makes the book feel like "Winds of War" with lizards.
A book such as this has so many opportunities to go into detail on how this alternative past is different than our own. The technology changes, the general life of the average American, Japanese, Russian, German, etc could be fleshed out more. In this alternative history, the US apparently goes to Mars. This is just mentioned in passing. What other types of technology do they have?
Another surprising thing is how little detail is given on human military technology. I know in our time line what 1960 era jets, tanks, and ships could do, what is different in this alternative timeline?
One of the most surprising things is how little mention the United States gets in the book from a governmental point of view. The reader gets no real inkling to where the US stands when compared to Nazi Germany or Russia from an economic or military balance other than a vague understanding that the US is "on par" with Germany in military technology.
Some things just don't make historical sense. In this alternative history, Great Britain slowly moves closer to Nazi Germany in behavior. I don't think many historians would agree that such a thing was even possible in a Churchill controlled Britain.
Even some of the character behavior seems senseless. The Race seems too ignorant to be as advanced as they are (not knowing how to deal with Snow? Even their home world would have to have polar icecaps and you'd think they would have been briefed).
But overall, my main disappointment with the book is that it's basically a 150 page book stretched into a nearly 400 page book.
But I would still recommend this book to anyone who enjoyed the original series. The original series suffered largely from these same things, especially the later ones). It's a good book but one that could have been so much better.