Fast paced, action packed, and very entertaining. Getting to travel, work, and fight a lot on horseback is excellent.
It's not a long, huge game by any means, but it's still a very entertaining experience and well worth playing in my opinion. I'm sure the developers could have easily made the whole experience last longer by slowing things down here and there and filling out certain things a bit more, but that would have taken away from it's fast, flowing, in-your-face style! It's not meant to be a slow, careful, drawn out experience.
And it was nice to be able to take a little break from all the intense fighting now and then and just head off and do your own thing for a bit . . . be it playing in poker tournaments, helping out at the ranch, searching out gold to mine, hunting a few beasts, using your horse to deliver things for people, and so on.
Gun looks good, sounds good, plays very well, and lasts long enough and has enough things to do to make it a top class game overall. And it wasn't as offensive or outrageous as I thought it might be. My only serious dislike would be for the first stage of the very last battle --- I found it to be a total pain and not at all appealing because of what I had to do to fight and damage the last guy (not one weapon or attack in my entire arsenal could inflict any damage whatsoever to him). But that aside, Gun is an excellent game! If only I'd actually been able to use a gun at the end. . . .