The one thing I loved was being in a passenger seat of a warthog while a friend drove on real treacherous terrain being chased by a ghost ‘n’ revenant (a custom game). While it was third person, it was scary for me (in a giddy way) and a lot of fun. Now, I think first person would add to that crazy giddy scary feeling and really put you in the hot seat. It would bring you closer to the battle and would look amazing too (be that for gameplay or a machinima movie). Also when holding the machine gun turret, I think first person (for this a custom game setting) would work too. It would feel more real to hold it and makes the player feel more… tanky… (Like Jorge, mah favorite Spartan).
Well those are just my ideas, what do you think?