Disclaimer: I watched Ryan play this and finish this. And aside from running into traffic, trying to jump off a satellite dish, and fucking around with the tow truck, I did not play this.
Very, very pretty. I mean that. Also, it feels very alive. Vice City felt...empty, like a deserted mall. This is the only other game in the franchise I'm qualified to compare this to.
My main observation was the story. I really like the characters and their development, though Michael is a jerk. Strangely, I like Trevor the most.