More or less a Jeffrey Combs vehicle, this variation of the "evil twin" idea features two new Weyouns (Combs), with one, of course, being evil and the other being good (which makes him a dangerous rebel in the eyes of the Dominion).
Good Weyoun gets the A story with Odo, a variation of the old "Sheriff taking the prisoner from point A to Point B" tale, which, as usual, allows for a lot of conversation. Auberjonois and Combs work well together, and after some character building banter, the writers give them something of particular interest to talk about that will factor into the future of the season. (There's also a nice effects sequence with their shuttle that's reminiscent of the Millennium Falcon's trip through the asteroid belt).
Meanwhile, the other Weyoun works with Damar (Casey Biggs) to stop Odo from reaching the Federation with his prisoner. Combs and Biggs are also particularly good together, better than Combs and Alaimo (which is probably the chief reason Damar has displaced his former leader). Biggs has an at ease style that works well with Combs's paranoid persona. As the two interact, Damar introduces Weyoun to a form of trickery new to the Dominion, and it's fun to see Weyoun head down the slippery slope and wonder where he'll land.
The C story is a comedy runner with Nog and Chief O'Brien that's really just a redo of Nog's scavenger hunts in "Progress" and "In the Cards". Despite that, the story works fine because it's mostly about O'Brien's reactions to Nog's offscreen actions (with Colm Meany having the best facial expressions), and it's short enough to avoid overstaying its welcome.
All three stories are nicely interwoven, giving the episode a nice balance between the comedy and drama. As they build toward their resolutions, savvy viewers will probably guess how each thread will end, but that's because there's only one way each CAN end. Nonetheless, "Treachery, Faith and the Great River" is a clever title for a fun hour of television.