I've been twice, only know of the bus option. Both times I rented a car but I did have a friend take the bus down to meet us on one of my trips. I recall it being slow. Sorry can't be of better help. Renting a car is pretty cheap (and strong dollar helps) so if your friend is ok driving it could be worthwhile (and less stressful) to rent depending on how long they're staying.
I've been twice, only know of the bus option. Both times I rented a car but I did have a friend take the bus down to meet us on one of my trips. I recall it being slow. Sorry can't be of better help. Renting a car is pretty cheap (and strong dollar helps) so if your friend is ok driving it could be worthwhile (and less stressful) to rent depending on how long they're staying.
My brother in law also took the bus. Prepare for motion sickness is his only feedback for the bus. My wife and I rented a little manual for pretty cheap and it was nice to go to more remote crags. Just keep in mind that Greeks, like people from Oregon and Jersey, don’t pump their own gas