This book kicks off yet another "alternative history" series from Harry Turtledove which is actually a slightly different rewrite of real history.
The basic premise is that there is another small continent or very large island in the middle of the North Atlantic, with massive natural resources, and which at the time of its' discovery by European fishermen in the late middle ages (in the 15th century) had no indigenous human population.
The new land, named Atlantis after the legendary lost continent, is fertile and quickly settled by British settlers, along with French, Spanish and Dutch settlements. The continents which we call North and South America are found a few years later at about the time they were really discovered, and named "Terranova" (e.g. "New Land"). Their history from that point, judging by tangential references in the book, appears to follow roughly the same track as in real history. But the main emphasis is on the story of the first three hundred years of the colonies in Atlantis.
In form this book consists of three linked novellas set at the time of the Wars of the Roses, 17th century pirates and buccaneers, and the Seven Years War respectively. Each tells of a key stage in the development of the colonies in Atlantis, as seen through the eyes first of Edward Radcliffe, who founds the first English settlement in the new land, and his descendants.
Turtledove once wrote that alternative history provides a "funhouse mirror" through which we can take a different perspective on real history. He has put this into practice: others have described his novels as having taken their plots from actual events but with different historial and fictional individuals and races playing the same roles.
For example, in his book "In the presence of mine enemies" a Third Reich which had won World War II eventually collapses in exactly the same way that the real Soviet Union collapsed. Similarly, Turtledove's massive eleven-book saga which begins with "How Few Remain" tells the dystopian history of a world in which the Confederate States of America initially won independence and survived for nearly a century but followed almost exactly the historical course which in the real world led to Nazi Germany adn the holocaust (subtext "Don't kid ourselves that we're superior - it could have happened here.") Other novels retell the story of historical conflicts like the American Civil War (Sentry Peak et seq) and WWII (the Darkness/Derlavi series) in worlds where technology is based on magic rather than engineering.
In the same way, the first three hundred years of the history of Atlantis in this book is remarkably similar to the history, up to the end of the Seven Years War in the mid 18th century, of the thirteen colonies which were to found the United States of America a few years later. This isn't really a completely different history, it's an alternative way of describing the historical background of the USA up to about two decades before the Declaration of Independence. The seeds of future conflicts - potential arguments between English settlers and the British crown, plantations in the south of Atlantis (originally created by the French and Spanish) which use slave labour - can also be seen in the novel.
It seems that everything Harry Turtledove writes these days gets praised by some of his fans and flamed by others who hate it. Although "Opening Atlantis is not a work of absolute genius like "The Guns of the South" or "The Two Georges," this book is IMHO one of Harry Turtledove's better novels. I liked the characters, I thought the action was well paced, the descriptions imaginative, the sequence of historical events broadly plausible. And he keeps his tendancy to repeat things too much reasonably well in check.
A sequel "The United States of Atlantis" has recently come out and I am looking forward to reading it.