We've been in Kastro in the middle of September, for one week. We didn't made any reservation. September is a low season month and we had several phone numbers of Samothraki hotels from the internet. Fortunately, our first choice was Kastro and they had no guests at that moment, but they were expecting a big group in 10 days. They know German as most of the people on the island, but at check in we had the pleasure to talk with an English speaker.
They were very kind and offered us a bigger room, at the price of a double with a nice view with the see and the pool. The breakfast was not included and not paid, because they usually prepared it for more than 20 people. Because we had a car and the distances are not so big, we could easily go in different taverns from the island to eat. There are also several supermarkets were you can find anything that you need or maybe forgot to put in your suitcase :).
They cleaned our big room every day, change the sheets and towels at each 2 days. We had a fridge and a drier; No plates or water glasses, but we didn't need them and I think it is not a problem to ask them from the kitchen. The balcony was very spacious. The only thing that was not perfect was the bath tube, because it was drained off very, very slowly, but this was not a such big problem. The pool was very nice, but the water was colder then the see and we preferred the see :) In front of the hotel there is a small, nice and stony beach, with clear crystal water.
We were planning to stay only few days at Kastro and then to move in the South. We felt very good in this hotel and we could easily reach from it all the interesting points from the island, so we decided to stay here all the time that we've spent on Samothraki.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.