Ok we started the OC yesterday and finished the quests in Neverwinter.  My bud started the OC with his Spirit Shaman level 5 and I started a new player.
When we finished playing I was level 7 and he was level 8.
It was really cool, coller than I expected.  Sure it help when you play in the same room so it might have added to the fun.  Gameplay was smooth and the game was easy to set up and/or join.
We played on a wireless network and everything went smooth, we were really pleased.
First thing, when one player pause the game, it pauses the others game too, so sometimes it can be annoying but it is a matter of tactics and when used well it's a life saver.  The reading part is well done too.  The player that initiated the dialogue is controlling the conversation and choose what he wants to say while the other played see on his screen the convo and the choices the other player make.  The quests are automatically added to every players journals and when completed, everyone receive the reward and XP.
From our first try, I must say it was really fun.