Okay just posting a few bugs that we (my husband and I) noted while playing co-op.
1. Questwise, the journals are not shared between player. I had no idea what my husband's character was talking about when our characters engaged in a conversation after he picked up and opened the Journal of the dead man at the start of the game.
2. If the host leaves the game while the player 2 is in the main menu, the game freezes for the latter. A connection lost error menu appears outside of the game which when clicked can freeze the whole pc until forcefully closed via task manager. After doing this and returning to the game, player 2 had the ingame pause menu layered on top of the main menu.
http://imgur.com/HpgrVUt3. Random lag spikes where the player will move one step at a time. Happens more often if one player initiates battle and the other is out of range of the battle.
4. This can also happen
http://imgur.com/JOqAJLR when one of the player gets out of stealth. The player is not actually at this location but further ahead.
Suggestion:
1. Maybe we should allow the co-op player joining to choose the class/character he/she wants to play as with the host having the right to veto.