At this point, the biggest surprise "The Sixth Gun" could deliver would be if there was a bad issue. Based on the work that Cullen Bunn, Brian Hurtt, and Bill Crabtree have delivered over the first nine issues, though, I think that's unlikely.
If you aren't reading "The Sixth Gun" then you're missing out on a mixture of horror, the wild west, dark fantasy, and yes, Cthulhu. In this latest installment, Bunn is adding to the mythology of the world itself. The revelation that the six pistols were at earlier points in time different weapons makes perfect sense, and the hint that doomsday lies behind the vault that they unlock.
But of course, there's more than just back story in "The Sixth Gun," as Bunn keeps all of his pieces moving. Drake's attempts to get information about the guns is coming back to haunt him in the form of attacks, and I like that Becky's new ally Kirby is proving to not necessarily be as trustworthy as he looked... but at the same time, there's still enough wiggle room that he can end up being hero or villain. It's that level of uncertainty that helps make "The Sixth Gun" stand out; Bunn doesn't just hand you simple answers to your question, but doles out the information over the course of several chapters, and inevitably nothing is as it initially seems.
And as for the art, well, it's kicking butt as always. From the graceful dance of fireflies in the depths of the swamp, to the multiple attacks on our heroes, Hurtt delivers. The assault of the owls on Gord is particularly impressive, with the swirling of beaks and claws and feathers looking disorienting as they flap through the room and down the hall. "Attacked by owls" doesn't on its own sound very scary, but Hurtt makes it by far the creepiest of the attacks, even more than ones by snakes or a panther. Now that's impressive.
"The Sixth Gun" is a book that leaves nothing to chance; every piece of dialogue, every carefully drawn background, it's all meticulously crafted and presented to us as readers. "The Sixth Gun" is one of the top comic book series being published right now. If you're not reading it, you're missing out on a hell of a lot of fun.