Decent but flawed
This game is kind of all over the map. There are parts the work really well, other parts that almost work well, and large chunks where it falls flat on its face.
I agree with Jeff's review that the story is one of the game's strongest points, but I still found it deeply flawed in many respects. I'm fine with having unlikable characters, but in the beginning I was supposed to sympathize with the two brothers - personally I have little sympathy for secessionist slave holders who have their humongous plantation burned down and their slaves freed, but maybe that's just me. And the early Civil War levels are some of the worst in the game, from a pure game play point of view. And the game's narrator, the good brother who's a priest, whines so much and has such an annoying voice (that you're forced to listen to during load screens) that I sometimes wanted to mut it.
But it picks up once you get out West and for the most part delivers on the promise of an olde timey shooter. I like that the 19th century guns slow the action down a bit, and the game's showdown minigame is pretty cool once you get the hang of it.
Worth renting if anything you've heard about it sounds interesting. Not worth it if nothing you've heard piqued your curiosity.