I feel like Infinity Ward had a 1 hit wonder with CoD4 and since then they've been trying to bury the franchise, and that Treyarch have been trying to redeem it somewhat. It's become like a rule of thumb that every second COD is decent.
This is of course speaking from the multiplayer POV only, and mostly on PC. The last COD I tried on a console was MW2 because it was so painfully bad on PC.
To elaborate further, I don't think I need to point out how good MW1 was. The few flaws the game had were easily corrected by fully moddable servers(case in point, pretty much any decent server had GL+LS disabled) and the community in general.
MW2 on the other hand was downright appalling. It did have the fluid gameplay and the quick paced gunplay of MW1, however it introduced IWNET - the single worst thing that hit the PC fps market in this millenia, no real time cheat protection, people cheating blatantly for months before they banned in "waves" and all the while consumers had to suffer through it. And it kept pouring salt on the wound, you enter a match with a rampant cheater doing 40:0 from his spawn spraying at walls, you leave and click matchmaking again only to be put in the same match, and again, and again. Until you give it a break or change the mode you're playing.
And then there is lag, oh the lag. The matchmaking system that puts people from central Europe in the same bracket with Russians from far east Asia. The matchmaking where every couple games a single player has the power to bend time and space to his advantage. And last but not least it removed to option for the community to control what they are playing, making nothing off limits and every idiotic feature choice of the developer available for use.
Black Ops was a breath of fresh air. For one the way killstreaks worked was a big improvement (to the one from mw2, it was still bad), the servers even though they were fairly limited removed lag from the equation and allowed some real time cheat protection to happen. Sure, good players often felt the wrath of butthurt admins, but it was still much, much better than the IWNET alternative. Everything else in the game was good or at least decent, except the theater mode which in my opinion was a great addition to the game, the game was a bit more technically rigid but still perfectly fluid on any decent machine.
And then MW3, one of the worst purchases I've made in my life. Rather than improving the faults of their previous game they decided to instead lie to the audience and make promises they never intended to deliver. For one,the promised "dedicated" servers they added were not ranked, removing the whole progression aspect of the game for anyone that played on them. And thus they were mostly ignored, except for the "cheater" servers where 1 kill would get you a bazillion xp and grant you a whole prestige. The theater mode was essentially ruined by removing the first person view on other players, the nonsense stacking killstreaks were back. (I do, however very much approve of the support and specialist streaks they added). But the final and the most gamebreaking point was again IWNET, they somehow managed to make it even worse. I've had games where my RL friend and I played with people from central Russia, western Europe, Mexico and Los Angeles in the same match. Not to mention the other problems that came back with the use of IWNET, I've seen more cheaters in MW3 in the first 3 weeks than in the first 6 months of BLOPS.
Black Ops 2 I haven't purchased but I've played a couple hours of it in a LAN center where I usually play coop and multiplayer games with friends. My first impressions were mixed, the killstreak system feels much better than anything else so far. I was sceptical of the new setting but I actually didn't mind it. The matchmaking is good in terms of lag, though I can't see it being any better than MW2 and 3 for cheater protection. Unless VAC people got their faces out of the cocaine buckets and started doing some god damned work. I haven't tried the zombie mode, but I have had a lot of fun with it in Black ops 1.
In summary, MW1 in my book is the clear winner of the COD contest. I thought the Black Ops 1 was decent, and Black Ops 2 similar if not slightly better. MW2 and MW3 I consider a bunche of potential wasted on bad technicalities around the game that make it uninjoyable to play.
Daym, I just wrote a wall of text about Call of Duty O_O
Can't even be arsed to spell check;/
