Overall you're left with an underwhelming experience. The game has some great ideas, like the co-op manoeuvres, but doesn't hit home with them. Instead it leaves them floating around in the park, crying out to be used better. Six missions is definitely not enough; a six hour single player game is not good enough in a world where gamers demand more from their experiences. Playing with a friend will greatly enhance the experience and will mean that tactics will be better used, although the AI will do a manageable job if you have no friends, but don't expect too many favours.
The multiplayer won't hold your attention for long when there are more exciting offers elsewhere, however it's there if three other friends fancy a quick bash at it. The game tries to be Gears of War, but falls far short of such an accolade. As it is, Army of Two offers an enjoyable co-op campaign with a friend and it's good fun while it lasts, but there's not a lot to return to here and you'll soon move on.