at E3 this year, EA have released a trailer, screenshots and plenty of details about the upcoming Vietnam add-on for http://www.trueachievements.com/Battlefield-Bad-Company....htm
The DLC includes four brand new multiplayer maps based on the Vietnam war, each bringing fresh visuals and characteristics, such as foxholes, tunnels and dense jungles. It also adds 15 Vietnam-era weapons and 6 vehicles available from the moment you go online. Included in that is the M79 grenade launcher, the Navy SEAL XM22 machine gun, the American Huey helicopter and the Russian T54 tank.
DICE have confirmed that the new maps will work in all four multiplayer modes in BFBC2, stating that the expansion is fully integrated with the full game, meaning that "no matter what theatre of war you participate in, you will continue to level up your soldier as usual."
To enhance the complete 60's vibe, man, DICE have also recorded all new voice-overs for both sides, based on authentic dialogue from the Vietnam War. On top of that, it'll included 49 songs of the "rocking soundtrack" to set the mood, including CCR's "Forunate Son," Buffalo Springfield's "For What It's Worth" (as heard in the above trailer) and "Ride of the Valkyries."
The Vietnam add-on will not be included in the recently-announced UItimate Edition of the game, but will release exclusively on Xbox Live some time this Winter. And yes, of course it adds new achievements - ten of them to be precise.