As level builders, Infinity Ward excel at organic spaces. Treyarch aren't bad designers, they just favour the artificial designs of the last generation - all corridors and right angles. IW's shopping centres, shanty towns and higgledy-piggledy villages feel like actual places where stories can unfold. Snipers stoop in bell towers, besieged teams hold up in quaint Paris cafes and lone wolfs find themselves stabbed to death in a lonely Asian back alley. You remember the places, not the blueprints - a rare sensation in multiplayer design.
It's also telling that MW3's best new modes favour teamwork over the lone wolf antics encouraged by Black Ops' Gun Game, Sticks and Stones and One In The Chamber.
Kill Confirmed is the star of the show. Earning points by grabbing enemy dog tags (and protecting points by grabbing your teammates') turns bouts into a deadly battle of wits. Teams deliberately leave dog tags to lure other players into the open, while long distance snipers send out teams of armoured scavengers to hoover up the rewards. A great cooperative event.
Team Defender, meanwhile, plays out like mobile king of the hill, with teams earning points by holding a flag, turning the flag into a mobile defence point. All of a sudden that support class makes complete sense, using points accrued with flag-holding to keep the team updated with UAVs and ballistic armour drops.
Being the flag bearer also puts you in good stead for Juggernaut mode, where 15 killers are thrown at one of the eponymous brutes. Utter chaos doesn't do it justice.
Only a foolish man claims to know how a COD will play out in the hands of the public. Playing in the confines of a review event we find a mode keen to step away from the lone wolf douchebaggery of the last few games. That said, douchebags are notoriously resilient, so time will tell.
The one place Treyarch truly trump Infinity Ward is Zombies mode. MW3's answer, Spec Ops Survival, isn't as honed. It's two blokes in a recycled multiplayer map fighting waves of AI soldiers. Collecting currency towards guns and perks ensures the fight evolves, but Zombies has the added advantage of custom-made maps and mechanics of its own.
That said, if your heart doesn't swell at the sight of five Delta Force heroes rappelling in to save your bacon from a pack of C4-coated dogs, there's little hope for you.
No tears are lost for Survival as long as you find a buddy to play Spec Ops' missions. There are less this time round - 16 to MW2's 23 - but they are longer and more substantial. The best of them demand co-op play - protecting a helpless buddy with a series of remote controlled turrets, for example, or protecting a bomb-defusing colleague from a snipers roost above.
It's also nice to see these stages filling in the gaps in the story - the jet you protect from hijackers in the solo campaign is the jet you try to hijack in Spec Ops.
Single player, co-op, multiplayer: put Modern Warfare 3 and Battlefield 3 side by side and they could be twins. Of course, online they behave like very different beasts and you won't be judged for pinning your colours to either mast. Put Modern Warfare 3 and Black Ops side by side, however, and it's clear who the older, wiser brother is.
Infinity Ward and Sledgehammer may be playing from the original Modern Warfare rulebook, but they understand it better than their Activision neighbours. Though, next time, it would be nice to see them add some proper amendments of their own.
And it might be time for Infinity Ward to overhaul their IW engine. It would take a very mean critic to bemoan a silky-smooth 60 frames a second - indeed, much of the 'wow' factor of bigger moments is that they transition so smoothly - but the engine is finally showing its age. Under all those great character animations and particle effects creak an old set of bones, hinted at in blurry textures and jagged edges.