Yelling at your team-mate doesn't work
Unfortunately, your AI team-mate and the opposition don't always behave as they should. Early on in the game I was treated to a rendition of the 'run around in circles dance' from my team-mate - delightful to watch, but not very effective in battle.There are also a few examples of enemies running around like headless chickens or behaving erratically, but one person I need to rely on is my team-mate because he's so crucial to everything I do in the game. On occasions, I've needed to issue commands multiple times because he's plainly ignored them. Perhaps the most frustrating of them all though is when he doesn't always heal you immediately when you get shot, but instead fumbles around or decides he'd rather take pot-shots at the enemy.
Although these problems are fairly infrequent, they do stick out like a sore thumb when they do happen. When the game is built around two-player co-op the AI needs to be spot-on. I can forgive the small problems with enemy AI, but your team-mate is your life-line. Although, I've still enjoyed the single player experience, it wasn't without it's moments of frustration and me yelling at the screen at my dumb team-mate. Therefore, I'd recommend playing Army of Two with a friend; you'll discover it's a far, far better game.
It's not all about just blasting away at dozens of enemies though, Army of Two is also about weapons and money. For every mission and side objective that you complete, you're awarded with cold hard cash to spend on upgrading or purchasing new primary, secondary and special weapons mid-mission. You can buy new barrels, stocks, shields, grenade launchers to pimp your gun or you can save your money up to get the likes of a rocket launcher.
Upgrading your weapons does have a significant impact on the way you play the game. Annoyingly, if you're playing single player, you can't choose your team-mates weapons, only your own. This would have been a nice little feature, but it doesn't adversely affect the game.
I tried to save up as much money as possible before splashing out on weapons, but it wasn't long before my HK 36 and it's slow reload time just wasn't enough to get me through a level. It was time to bag myself an AK47, with a grip handle, a magazine to hold more ammo and a new stock to reduce the recoil. Now we're ready to roll!
There are the usual array of weapons on offer, nothing special here: M249 Machine guns, shotguns, desert eagle, M107 sniper etc.., but they all bring something different to the way you need to play the game. Some weapons even generate more 'aggro' then others, whereas some suppress 'aggro. So, depending on your preference, you can really customise the whole experience. Pretty sweet.