Army of Two features some fun co-op gunplay, provided you have a comrade
The game emphasizes cooperation, and its objective is to bring back that classic cooperative gameplay trailblazed by predecessors like Contra. Unfortunately, Army of Two is nowhere near as iconic or memorable as its older brother, despite its 3-D advantage.
Still, the game offers a lot of intense, heated combat scenarios that require you to work as a team with your buddy. If your partner is shot down, it's up to you to make your way across the battlefield to revive him. Another feature is the "agro" meter, which allows one player to attract the attention of all your foes while the other player routes them. These two features compel you to fight together and work quite well. Other cooperative features, however, like co-op sniping and back-to-back gunning are quite clumsy and feel as if the developers were trying too hard.
The gunplay is pretty fun, though the weapons are highly unbalanced. This means that enemies can be extremely easy or extremely difficult to take down depending on your equipment. And speaking of equipment, you have a wide array of weapons to play with and to upgrade. These are all enjoyable features.
But all this enjoyment would mean nothing if you don't have a buddy to play with. I tried playing this game solo and quit after a short segment because your AI comrade is so dumb. Unless you micro-manage him, he will either run to his death or sit in the same place and watch you die. Single-player was definitely an afterthought here.
Bottom line: if you have a friend, don't hesitate to check out Army of Two for some satisfying co-op run and gun. But if you don't have a buddy to beat the game with, you should pass.