Too soon.
COD4 was a fantastic game, and the only COD game besides the first one that had my full attention (and I still play multiplayer regularly)
Then COD5 came along, in which Treyarch basically decided to try and regurgitate the brilliance of COD4, but with some added WW2 cash-cow milking and going back from the realism and gritty nature of COD4 to glorifying the second world war for the latest generation of kids that will have no sense of the horror their grandparents (or great grandparents) went through.
Now COD is back in the far more capable hands of Infinity Ward, but the series just doesn't appeal to me anymore when they start releasing a new 'version' every year. I would rather see one great, fresh COD per generation (4-5 years) than a whole bunch of titles with slowly degenerating quality.