Excellent, like all of Eric Flint's books, but this one didn't grab my interest as quickly as the others. It's a fascinating idea for an alternate history, but the first chapters merely serve to introduce the characters (and the entire book seems to be an introduction to the REAL story, presumably to follow in succeeding volumes).
Once you get into it, it's hard to put down. And, as usual, Eric Flint's characters are better people than real-life has led me to expect (though not unrealistic, for all that). You care what happens to them, and I'm anxious to see what comes next.
To be honest, it's hard not to feel some disappointment, simply because I was hoping for the next volume in the "1632" world. That's not fair to this work, of course. And now I can eagerly anticipate yet another sequel.