I found a lot of problems with it personally. Most of the content in the game didn't have a purpose, so there was little sense of progress or accomplishment for, say, spending an hour hunting, skinning and selling pelts.
The combat was functional but otherwise average and the missions were painfully linear when compared to the otherwise sandbox structure of the game.
The story, while having a phenomenal ending, was otherwise just Marston playing errand boy for about 25 hours. Until the ending ranch missions, it was just paced at a meandering plod.
It was still a good game though, in my eyes. The characters were fantastic, the world was beautiful, and the ending was touching, but I was expecting a lot more from all the hype surrounding it.