My problem with the panels was panels NOT being when or where they are posted to be in either the pocket guide or the changes sheet. It's annoying when you plan your whole day around a certain panel, only to show up and find something else there with no information as to what happened.
An update board with changes written in big red letters near the entrances would be nice. That way, if a panel was moved to a different day/time/location or was canceled, con goers would know as soon as they walked in the door.