I think Fassbender was perfect as well. One of the best actors in the world, IMO. Shades of his artificial character David in
Promethus and
Alien: Covenent. I see the purpose of his narration in the early part of the movie, but it became so repetitive and increasingly in conflict with the storyline. It more described his previous discipline. According to this article, it was a deliberate device David Fincher has used before:
https://screenrant.com/the-killer-narration-explained/