This is amazing. I'm not totally into open world games if I am honest, but this one just shows how great they can be when they are done well - and what an achievement this is.
Whether I played it in the true open sense I don't know - I did most of the challenges in front of me but didn't necessarily go looking for them, sticking mainly to the main story.
There is a tonne of stuff going on, and some of it is great - one brilliant scene in the pub springs to mind, but there are so many examples you could mention - it's all great.
There are bucket loads of narrative twists and turns, relationships and characters - some very creative thinking has gone into this.
The dynamics of riding the horse around is wonderful, you get emotionally attached to it in the end!
The story builds and builds, and the 'first' ending sequence back up a mountain is a great channelling of all the great aspects of the game, it's like playing in a Tarantino Django movie - just fantastic.