not great in February
I took the ferry from Athens to Naxos in Feb 05. I was supposed to get off at Paros but there was no announcement and it was such a quick stop there late at night that I missed it. I wasn't the only one to end up at Naxos.
My ferry arrived around 23:30 and I was fortunate the tourist office guy was still up watching a movie in his place because if he hadn't driven me to his mother's little hotel I probably would have been without a bed on a winter night. It seemed I was the only tourist in town!
The ferry was really the only thing about Greece I considered good value. Compared to Egypt I felt I overpaid for my Greek vacation. Greek weather in the winter was not different enough from more northernly climes to warrant it being a sun destination.