One of my friends in the industry has been playing the game (the ps4 dev one whose reviews are popping up now) since a week now, says he played for five hours and felt he still was beginning while another one of his colleagues 30 hours into the game says he hasn't stop seeing something or the other in the massive world and barely made progress in the main story. The game dives you in and said they can't wait people to play it.
Guess we are going to be just lost exploring and marveling at the world at the beginning.