First let me say that this is a good book, even a very good book. It's full of action, plot and character development and does a nice job of propelling the Ring of Fire story forward whilst opening up an already engrossing world even further with more possibilities. In parts it is damn well near impossible to put down as the suspense build momentum towards the end of the novel.
One of the things I've noticed mentioned about this book, and its predecessor is the nature of Oliver Cromwell depicted within. The recurring theme has been that many view him as a religious fanatic and thus find his inclusion and demeanour quite uncharacteristic in their eyes. However I would argue that Eric Flint and David Weber merely agree with the interpretation of Cromwell favoured by most historians not of a highly reactionary and right wing background. That whilst he was a deeply religious man, even to the point of zealotry, he was not in fact whooly defined by this, and was in fact a deeply complex figure wracked by his own deeply inherent social-conservatism which was at odds with his later religious radicalism. A radicalism which by our own standards would seem tame in comparison, and one ever at odds with his own interpretation of providence. Now in my opinion Flint and Weber hint at this, showing in Cromwells brief appearances his ingrained background as a member of the minor gentry (courteous, educated and polite), yet also showing how he is wrestling with his horrific treatment and loss in relation to God and providence. It will be interesting to see how they develop him further, and how he reacts to the American up-timers social-liberalism and importantly their own views on religion which in certain respects were no different from his own (As Lord Protector he maintained an informal freedom of religion so long as it did not hurt the country, as evidenced by the fact that he allowed Catholics in London to freely use the embassy chapels of the Catholic powers.)
Anyway, enough of that, in closing its a very good book.