I thought the original Call of Juarez was a better-than-average shooter that was bolstered by it being set in the Old West. I'm really surprised by the lack of western themed games given that for seventy-five odd years that was the go to "universe" for pulp stories and films.
Gunslinger isn't a sequel. It does use some of the same mechanics and has one level that supposedly takes place in Juarez. Other than that, there is no connection to Billy and the Reverend from the first game. In fact, most of the story here takes place in the form of a frame story and narration in which the Gunslinger is telling tall tales of his adventures years after the fact. Although well acted, the plot is just a means of getting the player from one area to the next without any real character development. However, the story telling becomes a game play device as the narrator forgets facts and has to backtrack causing the game to reverse itself or slow down to clarify a detail.
Really this game is all about the shooting. There's no stealth, no NPC dialogues. Just solid, fun and satisfying gun play. Even the dueling mini-game at the end of each level is a fun challenge as you try to manage your focus and hand position while waiting to draw. Adding to the fun is the the hint of Borderlands cell-shading style which complements the over-the-top Western Sukiyaki Django art direction and character design.