One single aspect? I know three ; Armor abilities, Dmr and Recoil. None of which we're in any of the other halo games but then ofc 343 came along. I'm not on OP's side saying it's the same game as Reach and I'm very much looking forward to continuing the campaing. But multiplayer Halo used to be 4v4, Br vs br and map control. True skill in other words. Halo 4 is just clearly not made for competitive gaming.
I am not posting this to complain, I'm doing it to discuss cause of what I've heard the general Halo community looks very much forward to this game and I wonder: Since CoD now also have the whole "Stay-out-of-the-way-and-regain-health" system and the only thing seperating the two is that Halo still is mainly 4v4, In what way do you see Halo Reach and 4 as an improvment from Halo 2 and 3?