The terminals. They should have just incorporated the terminal story into the main game. It explained ALOT of the back story of the diadact and librarian, and for people who have not read the books it makes the story seem a little crazy. For people like me it was ok because I read the books. I just feel like it is a needed part of the story for people who have not read them. To make matters worse you don’t even get to see the terminals when you find them.
Besides this however, this was the best Halo campaign to date for me, and I can’t wait to see where 343 takes Halo 5.