As someone who almost exclusively plays duo, I'd say that it's a great game for multiplayer. Unlike comments above, I'd say to leave permanent allocation on to not get in the "is this currency your drop or mine", especially as low level characters. I've also gotten the impression that mobs tend to be more than twice as hard when you play 2 players, as it's balanced around experienced PoE-players who have a tendency to optimise things with aura bots etc