OK, some multiplayer gameplay coverage now.
I've played a few times now on a couple of servers and it's pretty fun. It's basically the one from CoD 4 with diffrent setting, weapons and style.
Firstly - the maps. Easily said, some of them are the most beautiful multiplayer maps I've seen and I'm not playing on full detail (example - the Outskirts). The design is pretty chaotic, there aren't many maps composed of few corridors and some open space (like the Carentan map from previous games), so you have at least some freedom of movement.
Secondly - the weapons. Unfortunatly, machineguns basically own everything else. You can carry a MG42 and shoot it from the hip, while suffering little recoil. All heavy MGs behave more or less like this, so expect to be killed by them pretty often. There are new kind of grenades - Molotov cocktail, Tabun gas grenade (when your hit, your vision gets blurry, you move slower etc.) and sticky grenades for tanks. Then there's flamethrower once you reach level 65. Also, bolt-action rifles are back - and they work like a charm. Oh, one more thing - there is no nation restriction when it comes to weapons, so expect russians running around with japanese rifles and americans shooting PPSH. And to close up the section, bayonnets are in, extending your melee range.
Thirdly - game mechanics. Well, it's not much diffrent than in CoD4, so there's little to tell. Except for tanks beign back and capture the flag restored. Tanks can be a pain in the ass, because it takes a couple of bazooka shots to take them down. And there's WAR mode, something like Domination where capturing diffrent points yields diffrent results. The biggest problem are the spawn points, because it's pretty common to spawn in the middle of enemies. And one last thing - artillery replaced airstrikes and helicopter is replaced by dogs (which may or may not be less annoying - you can knife a dog or shoot it, but you'll often get attacked from both sides by them).
Overall, it's pretty fun, but it offers little more than CoD4, so I can't really recommend to buy it for the MP. If you already have it, but don't know if it's worth to play it, I say give it a try. MP gets an 8\10.