Army of Two is best played with a friend
Combat itself is a traditional 3rd person cover based shooter. Once a player looses all health, he falls down to the ground and cannot move, but can still aim and shoot while its up his partner to drag him out of the fight and revive him.
Sometimes you will be able to grab a riot shield and provide moving cover, as well as take a door off a car and use it in the same fashion. Some areas will give you an opportunity to fight back to back as you take down waves of enemies, while other levels might make you steer a parachute or a boat.
The graphics are nice, but the story isn't really engaging, and because it lacks any replayability and is pretty short, a rental is your best choice.