I actually liked GUN almost as much as Revolver and didn't have a problem with the horse, in fact riding around with the horse was my favorite part! I hated the last boss though. He's was so hard to beat and it wasn't very western like. You basically fight him inside some wierd cave or something.
It looks like Redemption will incorporate some Zapata elements into it. I wonder if the story has connections with Revolver at all?