With a small remaining community and poor balancing, Battlefield Vietnam has not aged well.
Cons: Extremely poor balancing; Small, divided community; Single player? Hah!
Many people think of Battlefield Vietnam like the war it recreates: a blunder that's better forgotten in the long run. However, I like to think that the game was once good (unlike the war). WAS, because with a small community emphasizing some already glaring flaws, BFV hasn't aged particularly well.
The basic idea is that of almost every Battlefield game: take a war (in this case, the Vietnam war) and allow up to 64 people to run wild with weapons and vehicles on a variety of maps, capturing points and draining tickets in the signature Conquest mode. I believe that this game also has another mode or two, but nobody ever plays it online and offline just pits you against brain-dead bots. So as far as I'm concerned, and as far as you should be concerned, there's only Conquest.
However, what's caused this one to age poorly is the lack of community. At any time you are bound to find 3 or 4 unfilled servers with a reasonable population. To make things worse, they are split between two patches, therefore ensuring that you only get 1 or 2 decent options. Given a lack of online choices the game gets stagnant quickly.
The lack of community can probably be attributed to the game's glaring balance issues. Although asymmetrical balancing often produces fun and interesting results, here it just suits the Vietnamese with inferior equipment in comparison to the Americans. Vehicles (particularly helicopters) run rampant, and even then one team gets the better vehicles. On many maps (including one particular community favorite), one team will even get more vehicles than the other. It all contributes to repetitive match structure as one team repeatedly gets hammered by the other.
It's a shame too, because Battlefield Vietnam vastly improves the level design of its predecessor (arguably BF1942's greatest fault) and implements a great idea with the foliage-influenced battles. In Vietnam, your nerves were likely to be wrecked as the enemy could come from anywhere, concealed by the grass, laying traps for your demise. Battlefield Vietnam recreates this sense of paranoia (and the satisfaction of a successful ambush) giving it one feature that has not since been recreated in the series.
Another area where Vietnam stands out from the rest of the series is in soundtrack. Namely, it has a licensed one. Picking from many hits of the Vietnam War era including "Hush," "White Rabbit," and even "Surfin' Bird," BFV brings together a rocking soundtrack that adds an extra dose of historical personality to its dealings. The series' typical longer loading screens and long drives are livened up by allowing you to hear these tracks. It's a really great addition and one that surprisingly was abandoned here.
Don't get me wrong, Battlefield Vietnam has its moments. The same chaos that the series is known for sometimes strikes, as you and teammates defend a flag from an invasion of amphibious tanks or you lead a strike against a base guarded by snipers laying in the brush, but it's not common enough. With the series growing as large as it has, Battlefield Vietnam really serves no purpose on its own. Perhaps it could enjoyably kill an afternoon if you get it in a bundle otherwise, but don't expect much more.