It's not even out yet - we haven't even played it for more than forty minutes - and Army of Two is already a guilty pleasure.
With Army of Two, EA Montreal believes it's struck on something that even the best co-operative shooters - like Gears of War and Rainbow Six Vegas - are missing out on: designing for co-op from the ground up. What that gives you is systems like Aggro - borrowed from MMOs, Aggro is the concept of drawing enemy attention in order to let your partner slip around unmolested.
According to Dustin Hoffman, Lawrence Olivier once explained his desire to act thus: "Look at me. Look at me. Look at me." That might not have much to do with Army of Two, but it does get you out of having to read a tampon joke, so there's no point whinging. Tampons are part of Army of Two's health system. Getting people to look at you is part of killing them all so very violently.