Fantastic game, but a few key flaws make the whole thing seem unfinished.
First off, the graphics in the game are just great. Nothing that will make your head explode with amazment, but still quite good. The animations are decent and the whole things plays without any noricable fram rate dips.
The music in the game in freaking amazing. The music is so epic, it almost brings a tear to your eye when listening to it while riding your hourse through the open plains towards the canyon lands. The voice acting is also very good, quite believable characters and dialog.
The gameplay is decent. The shooting system works well, and so does the riding system. What really brings the game down though, is it's length. The main storyline takes about 12 hours. The whole things seems very rushed and major plot points that should span several missions, are over in just one or two. Also, the side missions are all very menial and repetative.
Overall, a very decent game, with the frame work of a master piece, but it just seemed to rushed.