Battlefield Bad Company 2 is one of the top first person shooter games.  Bad Company 2 has been trying to wrestle the top spot in terms of online multiplayer first person shooter games from Call of Duty since March 2, 2010 when it was first released and now it has its first real expansion, Vietnam, which makes it quite evident that they are ratcheting up their efforts.
Included in this expansion are five maps and six new vehicles to command including a Huey helicopter (happily, the helicopter is not armored and can be taken down with some lucky machine gun fire or larger arms).  Fifteen Vietnam era weapons including muddied and battle warn machine guns and bamboo camouflaged rocket launchers are also present. 

The setting for Battlefield Vietnam is Vietnam (surprise surprise).  You fight your way through the steamy bamboo forests; flooded rice patties; and of course, local villages.
One of the characteristics of the Battlefield Bad Company series is destructible buildings and environments. This adds a fun dynamic to the multiplayer experience, no longer can a lone soldier hope to outrun a tank by entering a building, said tank can completely demolish the building around the soldier. Not only will you see building crumble and grass huts burn, but you will also see lush trees and plant cover fall away and leave you with a very grim open field where cover is a luxury and death flies by in a constant barrage of bullets, fire, and explosions. Near the end of a battle, a player can see first hand how the fighting destroys an area when comparing the before and after.

Another key component of the Bad Company series is squad-based play. When storming an enemy camp, it is important to work together.  Your squad is made up of medics, engineers, soldiers, etc. who need to organize into a united front.  A Rambo mentality (army of one) will not get you very far in this game.  When progressing through the game, you can level up via kills, points, and team actions.  These unlock more customizations, better guns, and other perks.

The multiplayer game types include: Conquest, Rush, Squad Rush, and Squad Deathmatch.  Conquest is a capture the flag match where players must keep control of three flags, for longer then their enemies.  In Rush, the players must either defend or destroy an M-Com station.  Squad based rush mode is similar and has two squads go head-to-head over an M-Com station.  And last but not least, Squad Deathmatch is a deathmatch mode with two squads and one vehicle.  Of the four modes, my favorite is Conquest.  There is nothing as satisfying as fighting your way through a band of soldiers and raising your own flag.  All the modes are fun, with the squad based modes being small with control, skill, and teamwork being of the utmost importance.