Although the overall experience does leave something to be desired, the core shooter mechanics are tight and satisfying. Getting around levels is easy, though every major move (taking cover, sprinting, jumping...) is mapped to the same button. The game is pretty good about figuring out what you want to do, though success isn't always guaranteed. Out of context moves are more common when the action gets frantic, though even when facing one enemy with a pistol, you'll need to be careful you don't accidently hurdle over cover when you intend to duck behind it.
Perhaps the best thing to come out of Army of Two: The 40th Day is the new combat tactics. Again, these work much better when playing with someone else (notice a pattern yet?), but even with the A.I., there's loads more strategy in the sequel. For instance, the duo can split up during missions, scout out situations and relay the information back to his partner. Info in HUD, they can then pull of dual sniper shots. Another new tactic is the fake surrender. When approached by enemies, one or both character can surrender. This causes the guards to relax, allowing for a quick kill or, if you're feeling generous, bind their hands.
It's clear EA Montreal put a lot of thought and time into trying to fix complaints with the first game. However, even with the improvements, Army of Two: The 40th Day can't seem to launch off the starting blocks. The 40th Day isn't a terrible game by any stretch of the imagination. If, like me, you enjoyed what the original offered, you'll be more than happy with the sequel. If you wanted more, or are looking for something different from other shooters, this isn't it. Despite the "buddy shooter" concept, The 40th Day is still just another 3rd-person shooter at its core; you just happen to have another gun at your side and some really cool tactics at your disposal.