The demo is out, and I took it for a spin. It's an interesting game, though I have yet to do all the things they claim are possible with it (set things on fire and burn your enemies alive, etc), but it seems reasonably fun so far. The game comes in two parts, one for each major character, Ray and Billy. Ray is a preacher who pulls out his six-shooters and goes on a rampage. He has limited bullet time that is activated when he pulls both guns from their holsters, giving him two reticles that slowly converge at the center of the screen. When they come together, bullet time is over. Combat is pretty lethal, so you have to make use of cover as best you can. Of course, this is the old west, so a lot of cover isn't that sturdy. Additionally, you can try to stun people by reading from the bible, but I didn't find this terribly useful in the demo.
Also, there is a quick-draw mechanic, pull your mouse down, then whip it back up and try to kill the other guy as fast as you can. In this showdown mode, you can't move, but you can lean from side to side.
In true spagetti western fashion, you've got two guns, right mouse fires the right gun, and left mouse fires the left gun. Since you've only got six bullets for each, you have to watch yourself.
Billy, meanwhile, is a sneaky sort of guy. He gets bullet time, but only when he uses his bow. He has a whip that can be used to grab things, swing around, and climb. He can mantle and sneak like Garrett from Thief, and his levels seem to be based more in stealth than raw action. Ray is coming after Billy, and so I think that a fair amount of the game will involve Ray cleaning up the messes Billy leaves behind.
In all, it looks like an interesting game. There's a fair degree of interacting with your environment, some physics puzzles, and general acrobatics when you're Billy. I've got my eye on it, how about everyone else?