CoD used to be a good series, but ever since MW2 came out, I have been having second thoughts about it. CoD4 will forever be the best CoD game ever, period. MW3 is just a MW2.5 with some changes. Seriously, some guns are the same, the HUD is exactly the same and what not. They don't even try to change anything. It's still the same boring run and gun formula. Black Ops actually introduced some player customization, which I think makes Black Ops stand out above the other CoD games since you can create your own emblems, display them on your guns, and more. With MW3, there really is no changes. Sure, attachments are unlocked through "leveling" up your gun, killstreaks are different, some guns and the maps have changed, you use prestige tokens to unlock additional features, etc, but overall the game has not improved.
When MW3 was first announced, I did not think very highly of it because I just thought to myself, "It's just another CoD game..." which it is, and i'm glad I never bought it. I played it on day one and was not surprised since there wasn't anything interesting about it. Black Ops is the only "latest" CoD game that I don't hate as much and was also the only one that kept me interested in it long enough that I prestiged to 1 within the first two days of it's release, then all the way until third within the next few weeks where I stopped because I like the third prestige sign.
The CoD series has only gone downhill and will continue to do so in my opinion, only because of the fact that Activision refuses to try anything new. They are afraid of losing their core player base when they have millions of people purchase their games. If they want to keep the same formula over and over again for future CoD titles, and not try doing something completely different, and I mean new to the point where it doesn't feel like a CoD game anymore, such as refreshing the series and starting over from scratch or something, then I will never buy a new title, ever. I am perfectly happy playing CoD4, World at War, and Black Ops when I want to play a CoD game, I don't need any newer ones that have no purpose whatsoever. Enough said.
I still hate the fact that Activision fired the two most important figures that made CoD4 what it was back when it first released. If they were never fired, I bet that the CoD series would be so much better to this day. Also, I can never understand why people love blaming InfinityWard for making MW2 and MW3 poor, it's not their fault. Most of the members of IW are now with Respawn Entertainment, and other members left to go into other companies. IW is basically Activision, just with a different name and group of people managing it. Activision ruined MW2 and MW3, not IW or Sledgehammer.