So, I've beaten the campaign, dealt with a number of things that made no sense (most of them because I never read the books, but I shouldn't have to read EU to understand Core), but there's one thing that's always bugged me since the second mission. Part of it stems from the redesign of the armor, treating it as pieces to be used in Infinity Multiplayer on top of campaign. However, something in this game felt out of place: Armor Mods.
We have never seen Master Chief use anything like these in any game prior to this (Halo:CE, Halo 2 and Halo 3). While the mechanic was introduced in Halo Reach, it still doesn't make sense that he is all of a sudden using them when he has never done so in game before. It felt forced, almost as if 343 only put it in because they were in Reach. I would much rather have had them not in campaign at all, or have an actual armor "upgrade" take place when he made it to the Infinity. As it is, it doesn't sit right.
Also: How is it that Cortana can ID the Promethean Tech before even touching it? We kill a crawler, and it drops a Boltshot, and instantly we know that it is called the Boltshot and has 10 shots before being reloaded...