I had a good few games the other night. In free roam, a 'post the bag' event appeared, and people scrambled out of Blackwater to get it. There was a lot of murder and it was a clusterfuck, but after the event had finished, everyone stopped fighting. I was pleasantly surprised.
I really haven't seen much random griefing. It's nice.
I'm really enjoying the showdowns, I've only played large showdowns but did they take out the way that showdowns started in RDR1, with everyone facing off across a street? Maybe it's in the smaller showdowns.
I'm loving 'name your weapon' where tomahawks and explosive arrows(!) cause chaos. Nothing more galling than trying to tomahawk someone through a doorframe only for your tomahawk to clunk off the top of the doorframe in front of you. Woops.