I'd like some actual innovative mechanics. Other than mobility, you can't argue that there are any new mechanics that are different from any game from 2008. You also can't argue that compared to bungie's earlier work on the halo series, that the story mission level design and narrative aren't completely lazy and utter shit. It's stuff like that which adds massive replayability. It just feels so bare bones it's embarrassing. What it comes down to in my opinion is that the bungie crew now isn't the same crew as worked on halo, they are on a huge time constraint and the project of building the proprietary engine itself took longer than they thought. So either they forgot how to make an AMAZING game instead of a good or ok game or they are just piss poor at time and resource management.