Battlefield: Vietnam feels more like an expansion to the over-expanded Battlefield: 1942. When you first pop in this game, there is something there that says "I've done this before."
Single player in BF:V is non-existent really. There is no real story line... but would you really want to play a game where you ended up losing no matter what? All single player is, is a mock online game. You chose the settings of how smart / stupid you want the AI of the computer players, pick how many bots, pick the map, and jump right in. This is good, as it lets first timers get ready for online play, but it's not enough for veterans to the (now) series. This also gives you a chance to train on the new planes, choppers, and other various vehicles; before you get yelled at for wasting time online.
Multiplayer is what this game is about. It's very easy to jump in game, and have instant fun with up to 64 people. Maps range from deep jungle maps, to city maps, to airbase battle maps. You can chose from a fighter, engineer, ranged fighters, or sniper as your play style: Fighters get accurate short range weapons. An engineer get utility weapons, such as land mines, wrenches for repairing, and even shovels for moving around certain spawn points. Ranged fighters get rockets, and grenade launchers. Finally, Snipers get... sniper rifles! Most of the time there is no 'right or wrong' class to chose, it just comes down to what you like, or what you can have fun with. Even with the choices, gun balance really gets to most players online. The American team has the ability to get the M60 weapon, and chances are if you play online, 75% of people try to get on the American side just for this gun. The accuracy, range, and power of this gun are just unmatched in one-on-one combat.
Now, you may think "Why would one-on-one combat matter when so many people can play?" This had to do with the map choices. There are certain maps, which are just too wide-open. Battlefield: 1942 most of the time had choke points, where battles would be centered around. That is no the case this time around. You can right down the road, down the brush, or far away in the trees, and not see another player for minutes. Also well, there is a lot of cover in this game, such as bushes, or large rocks so get ready for some deaths when you never saw where you got shot from. Playing in a Jet, or Helicopter can be very fun, and aren't too hard to pick up on, but it takes a great deal of skill to be good in one. However, once you get past the basics of flight, these airborne vehicles are nothing but death from above. Some pilots seem unstoppable in them, no matter what you do. Shooting at these people doesn't do any good, and just gives away your position.
A major flaw most people saw with BF: 1942, was that the graphics were just too laggy online. Thankfully these issues have been fixed for the most part... but if you decide to play on the 64 player servers, get use to the same thing all over again. The minimum requirements for the game are listed at 933 MHz, but that's probably what you need to have, just to make sure the menus will load. Even on my computer, there were times I would get graphics lag (specs listed at the bottom of the review).
Sound is normally something I don't comment on too much, but this game does a very good job of making use of it. When driving a vehicle around, you can set the radio station, and play a wide variety of "oldie" hits from the late 60's - early 70's, that the old or young will recognize. Playing with stereo speakers (or surround sound) can really help in finding where people are trying to shoot you from as well. My only miff on sound is the in game overhead speakers, that shout propaganda over the entire map, and there is no way to turn of it off at this time. While I understand it was a large part of the war, it gets very annoying during game play.
Battlefield is a good FPS, but definitely not for everyone. If you liked BF: 1942, chances are you will like this too. For newcomers, try checking out the BF: 1942 multi-player demo... it's not that much different from this. It's not so much of a game of skill, than a game of "I saw you first."