Alternate Universes...great when done right.

I'm a little ambivalent on Eric Flint's world.  First of all, his setup powerfully strained my suspension of disbelief.  I mean, really: a race of techologically powerful aliens whose works of art were dangerous to the worlds around them because of the way they flung the waste around managing to hit a small, coal mining town in West Virginia carved out a six mile wide sphere of land and air above it picking it up and dropping it in Germany in the middle of the Thirty Year War.  It's really hard to close my eyes and believe that. 

I'm not a big fan of that particular time period, either.  Protestantism is still fairly new, and the conflict between the Protestants and the Catholics is particularly bloody.  Feudalism is starting to collapse in a rather bloody fashion, and literacy is patchy--unlike (surprisingly) the early Medieval period in Britain. 

Third, I am not now, and likely never will be a fan of modern unions.  You have to have a situation as unlikely and extreme as the book's to make a modern union anything other than the next best thing to a Medieval guild in the level of uselessness and oppressiveness.

Those aside, the Ring of Fire series (starting with 1632) is well-written, with truly unique characters discovering that the veneer of civilization that covers those in small towns is truly thin--and that's not necessarily a bad thing.  Like any small, Appalachian (or Midwestern) town, the number of small arms outnumbers the people: not a bad thing when that town is suddenly and inexplicably dropped into the middle of a war zone where the Geneva convention hasn't even happened yet. 

And the town, Grantsville, refuses to blend into Germany of the time, choosing instead to begin the American experiment nearly two hundred years early, and on the wrong continent.  1632 is the story of the emergency and response, the setup of a new republic, and the small amount of breathing space they won.