All of it, there's not one thing i haven't liked so far.
It's like being part of a movie, it looks so realistic, but at the same time is like living in the times,
One nice touch is being able to add to your "fame" by helping out people in distress, Like not the help a citizen side missions, but i was riding to the next town and i saw someone being attacked by coyotes so i helped them out, and got extra fame and a few dollars, and once i came across a guy defending his farm from bandits
Also i got ambushed by bandits, i thought it was a normal stage coach then armed men were everywhere suddenly
and just the bandits in general, how you'll go into a town and they'll be raiding it
and being able to choose whether to go a mission "good" or "bad" which then effects your reputation
Gah, i just love it all