I was asked to post my experience in Oia during my winter visit (16-21 February) so here we go.
I'll start by saying that I decided to go to Oia now because I was looking for a place with incredible views and not many tourists. To inspire me to write (I'm working on a film script) and to relax since I just finished my exams. I'm not a fan of swimming and tanning so lack of sun didn't bother me.
I took the 7+ hours Blue Star ferry from Piraeus to Santorini which arrived in Santorini late afternoon. I enjoyed the ferry, felt a little seasick during but I enjoy long journeys, I liked seeing the island on the way. I paid a little extra to get a seat in business class and the service was great (though all the food and drinks still cost money of course). Don't pay for the wireless internet there since it didn't work for me at all during the journey (not on my laptop nor my phone).
In Oia I chose Alexander Boutique Hotel's because of the reviews I read here. I'm a solo traveler and often fear I won't be treated as well as those travelling in pairs or more, especially in a place that's so romantic. So the reviews I read here were all by solo travelers too.
The hotel arranged a transfer for me from the port.
I can't begin to talk about how much I enjoyed the hotel, I wrote a detailed reviews on it (still pending, will probably be published soon) and I urge anyone looking for an hotel in Oia to read it - tripadvisor.com/Hotel_Review-g482941-d283496…
Oia was everyone I wanted it to be. Visually stunning from every part of the village. I often found myself just walking around aimlessly, sucking in the views. I enjoyed going to Oia castle everyday long before the sunset just to sit there, listen to music and read. Closer to sunset hour plenty of other tourists arrived even though it's winter (I'm guessing in the summer there are many many many more).
95% of the shops in the village were closed. I saw a couple of open restaurants, I ate in Lotza almost every day cos I really enjoyed it (wrote a pending review on it too), didn't try any other places in Oia. Very few shops were open - a couple of memorbilia stores, jewellery stores, the beautiful Atlantis bookshop (where I bought a book for great value) and some supermarkets, where I bought some food to cook in my room when I'm on a writing spree and don't feel like going out.
Despite there not being much to do in Oia, I didn't want to leave for several days. I fell in love with the view and general atmosphere. I enjoyed the quiet and loved walking in the empty streets where you rarely see another tourist or a local, and mostly see cats and dogs (who are all friendly enough to play with).
Eventually I took a bus to Akrotiri. For a history freak like me it was worth it, not as impressive as Pompeii and still, very cheap to see and learn so much about this place. Also walked a little further to see Red Beach. A local tavern (The Dolphins) next to it was open, even though there wasn't a single soul around, so I had lunch there, the people were very friendly.
Also spent a day in Fira, a little more open shops than in Oia. Loved Lucky's gyros that everyone on tripadvisor recommended me but honestly, I just wanted to go back to Oia. I love the atmosphere there and I actually felt that despite Fira being rather empty too, it was "too crowded" for me after Oia. I really enjoyed the bus ride there though, the drive on the mountain was stunning. I was considering renting a car but because I liked Oia so much I didn't see the point. I think for winter travelers renting a car would be much easier though since the bus schedule isn't from Oia to Fira and then Fira to other parts of the island wasn't very often. Renting, at least right now, is also much cheaper than taking a taxi everywhere.
I worried I won't get to see the famous Oia sunset in all its glory since there were a few cloudy days but luckily the day before my flight back was clearer and the view was stunning. Also in one of the cloudy days it was raining and we got an amazing rainbow that went all the way around Oia.. that was another breathtaking view.
Some people I met during the trip went to the volcano so a boat trip there was a possibility but I didn't go for it cos I was dreading getting on a small boat with those waves especially after feeling seasick on the big ferry (it made my first day in Santorini a little difficult).
Basically for people like me, who like quiet, who seek relaxation, inspiration, who want to enjoy the views without the crowds, and don't mind the possibility of no sun (and maybe no sunset, I was lucky..) and no swimming - winter is perfect. If you seek shopping, sea and sun, do summer and brace the crowds.