Also I don't understand why everyone is saying there are no big battles? There are some large battles but also this game was made to be stealthy. It was said that you are a special forces team and a bunch of shot down guys behind enemy lines, there was never going to be huge offensives like the previous games.
It was always going to be small squad based combat which I personally think is awesome. It limits what you can and cannot do and really makes you think, e.g. do I equip this guy with an RPG or have him carry extra MG ammo for the MG gunner in case we come across a swarm of infantry.
Also loved the mission where you sneak in to the Vietcong base and mine their tanks and supplies. Replayed it yesterday with 100% stealth
