Eh, I can't help but be incredibly critical of this game, not because I hate it, I mean, I prefer battlefield, but I do like CoD.
This game is supposed to be the best of the best, It's supposed to slay giants on release day to compete with some of the biggest selling games of the year. It's supposed to be design perfection, and professionally polished to the highest of the industry standard.
Using an old engine isn't the sort of polish that the series needs, it needs to be seriously invested into becoming the fastest selling game ever. It needs to supersede in every area, and I'm sure that the game won't do that actually, and on top of the old engine, it definitely won't do that.
Sorry CoD, but bad move. Nothing less than greatness will be expected, and you probably won't get that.