*SPOILERS*
First off, lets start with the story. The story seemed bland, for the whole game you were tracking down a single enemy. When you find him, there is no boss battle whatsoever. He just gets killed off by Cortana. Secondly, most enemies came very unsuspectingly. I haven't read the books, but there should atleast be some explanation to fighting elites.
Now for the music. For me, the music plays a big role in the campaign. Unlike other Halo games (except Reach) this game lacked dramatic music. To me that changes my whole perspective of a certain part. I really wished they would have added music from previous Halo games.
Lastly, the gameplay seemed very repetitive. Although previous games didnt have much of a variety either, this one seemed like neverending meetings with Prometheans. It didnt help that on legendary they take a few clips of almost any gun to take down.
In all, this campaign falls in one of my least favorites. Remember, this a community. Everyone is entitles to their own opinion. Tell me what you think.