I really enjoy how the difficulty slowly progresses and it never feels unfair, because when the game introduces a new mechanic or a new trick, they do it in a very easy level to get acquainted to it. Still the game is quite challenging and keeps the interest in the story too, which is a bit uncommon for this genre, I always wanted to check how the computer would interact with me, or what the narrator would say in a new level.
Amazing experience overall.