I don't know about the ghost, but I've played a lot of the classic mode, and it's challenging unless you're in great shape. Three minute rounds, and you're dropping in your corner gasping for breath. I've been able to beat all the opponents on normal, and an halfway through them on endurance. You've got to keep your guard up, you've got to keep moving your feet, and you gotta be quick. Remember not to fully extend, you won't get actual resistance so it takes some practice not to hurt yourself. It rewards accuracy over power, but accurate heavy hits are key later on to get knock outs.