I only read the first two books in my youth, but I feel that Lost Regiment is sort of a love it or hate it series; it has a good amount of Civil War stuff if you're into historical fiction, but it is very abstract and requires a bit of a leap of faith as far as the premise is concerned. I loved the action and the dialog, which I feel Forstchen has a very firm grasp of. Colenol Kane is a very likeable and real-feeling character in Rally Cry, and definitely brings the story into perspective. I say pick up #1 for a couple of bucks, and if you like it, keep reading. I think there's 9 or 10 books currently in the series.
And if you're into Civil War alternate history, definitely check out Harry Turtledove. Guns of the South is a classic, as is How Few Remain.