A book that I enjoyed quite a lot, so quite recommendable. The details are presented bit by bit so you may think in some overlapping multiverse when it is something more mundane. And that is what makes this the more interesting, indeed.
The setting is a little bit tricky, although works out quite fine, so you may overlook some of the problems that it might arise if in the real world. But this is fiction and one of the best on alternate-history I have read. I will not complain, but for the conclusive last chapter. There, the history loses the charm you have involved in throughout all the previous chapters. If not disappointed, I might say you may feel that the plot deserves a better ending. That's why the forth star is dropped on my rating.