Two words can describe this game with 100% accuracy: Cash Grab
Much to my disappointment, Infinity Ward has used the opportunity that is COD: Modern Warfare 2 to not improve upon COD4 in any meaningful ways, but instead to cash in on the misplaced COD popularity before something better comes along. It's just a real shame that no other developers have tried to mount a serious challenge to COD, because it wouldn't really take all that much effort to do so. I'm sure a few garage MOD groups could fix up something better than this junk.
For starters, I want to touch on the throw away single player campaign. I won't get into much more than this one paragraph, because just like COD4 the campaign mode is completely forgettable, and quite frankly I would have bumped the score I'm handing out here a little bit had it been removed entirely. Much has been said about the "gripping" and "intense" campaign that this game forces you through, when in reality it's more like "boring" and "contrived". The campaign is just a poorly written and cliched extension of COD4's campaign mode, meaning it's oozing with X-trEME BADItude. The characters are forgettable, and more annoying than anything, and the mixed up unintelligible story simply goes about setting up tent poles to give excuses for putting different levels in different scenery. To make things worse each level is linear like Super Mario Brothers and has a sprinkling of painfully overdone "action" sequences that invole nothing more than scripted FMV style "gameplay". Yes, all of the quotes I have used so far are more than appropriate, and grammatically correct. Nothing about the campaign has been fixed from the horrendous COD4 campaign. Poorly designed bits that are still intact include dumb AI, endless enemy spawns, absurdly impossible feats of heroics, and worst of all ENDLESS ENEMY SPAWNS (in case you missed it the first time). How on earth a game released in 2009, let alone 2007 can feature enemies that spawn endless forever until you cross an imaginary goal line is flippin' ridiculous. Too make things worse, most of the achievements from the game are buried deep in the bowels of this atrocious experience.
Moving on...
Spec Ops is trash. There. I said it. This mode is nothing more than a half-assed thrown together attempt at co-op that Infinity Ward tossed out as a bone for all the requests that were made for a REAL co-op mode. Unfortunately it falls flat on its face. These levels are pieces of levels from the single player campaign chucked into goal oriented gameplay. I've said it a hundred times before, but I will say it again. When you have to put an "arena" mode in your game, you've run out of ideas or the motivation to think outside the box you've put yourself in. This is where Infinity Ward is at right now. They haven't done anything innovative to the COD series for about 4-5 games in a row, and Spec-Ops does nothing to change this. At least they tried... I guess.
The Multiplayer can be summed up rather quickly. Broken. COD4 was a mess for a litany of reasons. The worst offenses were easily the atrocious hit detection coupled with the terrible hitbox lag. If you don't know what hitbox lag is, it is easy to explain. What you see on your screen and what your enemies see on their screen is actually where everyone else was half a second ago. Most games get this down to a lot less than half a second but COD4, and now MW2, manage to get it all the way up to half a second in most games. This presents itself in numerous ways.
The first complaint you will hear in game is that someone is shooting curving bullets. This is because the person that died ran around a corner, but still died. This happens because the person shooting at them is actually shooting at where they were half a second ago (as they see them on their screen). Just think of it like this: You, as a target, is half a second ago from where you are now. This is a huge penalty for those being targeted, but a huge benefit for those doing the targeting. This makes the gameplay behave nothing like real first person shooters (that's right, COD is just a pretender) because the players aren't competing against each other out right. They are competing against the game by getting the timing down for how much lag there is. It pays to move and move fast because if you jump around a corner at full speed and see someone sitting still, you have a full half a second to aim and start shooting before they see your character model run around the corner on their screen. You make think this is fantastic because it reduces camping, but sadly it does not. It amps up camping because everyone constantly looses to those moving really fast, and it encourages speed stabbing which does nothing but drag down each multiplayer game into a very routine and predictable round.
The second worst thing about multiplayer is the painfully piss poor hit detection and damage calculations. On the regular mode (not hardcore) this game takes TWO shots to the head, or more, with everyone weapon to score a headshot. Except for sniper rifles through a scope. That's right, you can shoot an enemy in the head from point blank range with a .44 Magnum and they won't die. Stupid? Yes. Abso-frickin-lootly retarded? Of course.
The hit detection seems to be based completely on randomization. You can light up an enemy from 15 in-game feet away with an SMG, with your targeting reticule right on their back, and pump an entire clip into them only to end up reloading and get no kill. They will then turn around and in some cases kill you with the exact same weapon in 2 shots. Why some enemies are indestructible and some are not is truly a mystery. To say it feels cheap and badly designed is an understatement.
I don't know if I am capable of describing how insanely stupid the killstreak rewards are in this game. There are a few dozen problems that this component of the game brings, but I'll keep it down to pointing out the most glaring. For starters, it doesn't matter what game mode you are playing, every round is deathmatch. The reason for this is the 25 kills reward lets players set of "tactical nukes" that obliterate everyone and score an instant win for the team that was lucky enough to have some random dude camp, stab and nubetube his way to a 25 killstreak. Domination? Nope. Just another deathmatch round. Doesn't matter if you are winning or not when that nuke goes off.
The second problem this creates is that it pulls all of the shooting aspect of the game right out of it. Those 25 kill streaks can happen when only 5-6 of the kills were with an actual gun. This is because Infinity Ward thought it would be a great idea for rewarded killstreaks to stick around and stack up for use. The end result is a never ending stream of air support, air strikes, helicopters, predator missiles, more airstrikes and 3 more helicopters to finish off your round. To top THAT off, the air support AI is some of the worst spawn camping garbage I have ever seen. It's routine to come back into the game only to get sprayed to death with the air support's perfect targeting. You can't run from it, you can't dodge it. The only thing you can do is hide under something and hope it goes away. Unfortunately it comes right back mere seconds after it's done because the killstreak rewards are painfully easy to earn.
Don't even get me started on how insanely stupid it is that you can long distance kills while running around with a shotgun in each hand. The "akimbo" unlock is probably the biggest new failure for the game. It's unrealastic and has quickly become the default configuration for well over 50% of the people playing the game because it's so insanely overpowered. It's basically like running around with a one-shot guaranteed kill. How on earth did that make it past play testing? I bet some CEO at Infinity Ward insisted it remain in the game because it was his favorite, and here we are. Unbalanced mess is go!
The spawning system is also fundamentally broken. The game will attempt to spawn you as far from the highest concentration of enemies that it can, but most of the time this doesn't work, or it spawns you out in no man's land and you have to run your way back to where the action is. I've frequently been killed instantly after spawning my gunfire. For some stupid reason the game can't detect that your spawn point is being covered with enemy gunfire and will drop you back into the game, along with a brief moment where you are in the game but can't move yet. Prime pickings for the spawn campers and air support floating right above you.
The end result of most of these problems is that you will have games where you are completely on fire and just destroying everyone with your arsenal of missiles, air support, and occasional firing of the weapon (if you get lucky and don't get hitbox killed). Only to turn around and have games where you can't take two steps without dieing to the exact same stuff. The level of balance in the game is way off. Why the game chooses to reward those that get up first at the beginning is a mystery.
In summary, this game is nothing but a completely over hyped, overrated, shoddy piece of crap disaster. Don't bother picking it up. It's painfully unfun, 95% of the time, and will do nothing but make you want to take your 360 back to where you got it.
I forgot to mention the positive about the game. It looks pretty darn good, but not all that much better than COD4. It definitely looks and feels recycled and everyone that bought it should feel upset that it wasn't released as a 400 point "upgrade pack" because it most certainly would have fit into one.