First let me applaud the fact that those screen shots are full actual resolution 1280x720 That's worthy of some
Next let me point out that there isn't a Jaggie in site... the models are crisp and clean. The carriage in the first image is a little rough around the edges (literally) though I think those are more texture issues than jaggie issues (remember MSAA only effect the edges of polygons) you'd need some AF to fix problems with textures.
I'm not much of a western fan but the game does look very interesting. I might rent it but I don't know enough about it yet to decide to buy it or not.
All in all the graphics really aren't that bad. The models might be lacking detail but it makes up for it in scope. Not to mention they did a VERY good job with making objects have the same reflectivity/radiosity properties as they would in real life as opposed to everything just being shiny (which is really important for a western, because there really wasn't much shiny stuff around back then
I think the biggest leap from this gen to next gen is thing like Reflectivity, radiosity, lighting and particle effect, etc. The problem is most people don't seem to notice or understand these things. I've seen comparison screen shots were one image made use of all these things and the other didn't, it was a night and day difference to me but almost no one else could tell the difference.