Just finished off my first MP session of 3 hours, and i have to say the game is mind blowing. Bc2 doesnt come anywhere near BF3 on any area.
Graphics are really good, and most importantly, it runs smoothly: i'm using ultra settings and i'm getting pretty much constant 50-70 fps on 64 player conquest server, sometimes it dibs to low 40's when there's alot of action. I think the lowest i saw was around 35 on caspian border, that map seems to be the biggest performance hog.
Gameplay hasn't really changed that much from the beta, but one thing that i noticed is that the gun damage seems to be toned down a bit, maybe 1-2 bullets on average more to take someone down. Oh and the commo-rose is in, which was a nice surprise.
Audio is amazing, i was having some sort of seizures from the pure sensory overload on some map which had a huge cave inside a mountain, and 64 players hammering each others on that closed area, the constant barrage of bullets, granades and tanks blowing **** up was just about the most impressive thing i've experienced in any game.
Only complaint i've got is the map desing. Fairly large Conquest maps, yet the capture points usually are in a really tight cluster, rather than spread out on the map, which pretty much makes rest of the map just a nice scenery, without any real purpose.
Didnt notice any gamebreaking bugs, some server lag's here and there, but most of them seemed to run nicely.
My personal GOTY 2011, i'm ready to say it, even if it is only after 3 hours.
EDIT: Based on the couple of the first mission's, the SP is really a turd, it's like cod, but worse. Then again who gives a **** about SP in a BF game.