I never played any of the games in this series. I read up on it and it seems like it'll be pretty cool, so preloaded it is!
The key to this series - what makes it stand out above the crowd in that playing on public servers (IE., not clan or ladder servers) tolerable - is the 'honor' system.
If this is like the previous games, after completing the more-or-less offline 'basic training', you'll ultimately end up with something like 10 honor - it's persistent to your account. You GET honor by achieving objectives, staying with your squad, helping wounded teammates, etc. You LOSE honor by violating the rules-of-engagement (killing a civilian, for example), shooting teammates, etc.
Some servers will even set up a threshold that, for example, you cannot even join them without at least 20 honor....some are higher (I seem to recall a few 50 honor servers out there).
Another interesting thing about it is that your squad has so many slots for each 'class' (although that, in this game, basically just determines rank and weapon you carry - nothing different about your character, and every weapon in the game is perfectly capable of a one-shot-kill if aimed properly). One squad leader, a few fireteam leaders (with some fireteams being just riflemen, a sniper or two, and a machine gun or two). You request what slot you want. If another person requests the same slot...whoever has the higher honor gets it (the other guy is just a rifleman, then).
It kinda sounds like it would be unfairly biased towards long-time players, but it doesn't usually feel that way. True, the squad leader position usually goes to someone who's been around a while...but that's basically the way it should be (it's how it is in the real Army). The other positions are more open - it helps that the default rifles (the M16A2 or M4A1) are not gimped in any way in this game. They are really good guns.