The single biggest difference or challenge I see so far is the channels. It's easy to forget to check the channel you are in when grouping or meeting others in the game.

Changing channels is not immediately evident and you have to navigate to a menu to do so. This menu is also not accessible from the main menu which means hunting for it at first.

Beyond that the idea of instanced zones is kind of interesting. In a zone with too many AFK shops, gold sellers, or just people? Zone into a new channel and watch them disappear. Takes the frustration out of congested zones when doing quests (also makes an easy way to get away from gankers chasing you).