We had a lovely stay at Stathis and Maria's lovely little studio/cottage. It's a pretty one room dwelling next to their house, so they're on hand if you need anything. Maria took us from the ferry to the cottage, sorted us out a good value hire car and settled us in, giving us some useful tips for our stay. There was food in the fridge for us, which was very welcome after a long journey. The bed is in a little curtained nook, there is a bathroom with shower and clean towels, and a lovely sunny outside terrace to sit on and enjoy the view. Everything was clean, comfortable and stylish.
I'd say that it wouldn't be an easy place to stay at without a car; the nearest little seaside town (with plenty of eating places and a couple of useful shops) is a good 3km away. With a car you can use the cottage as a base for exploring this gorgeous, unassuming, quiet and traditional island but it would be difficult to stay here otherwise. We found some great little beaches and seaside tavernas within a few miles drive; nothing is very far away on Syros! It's a wonderful island if you want the peace of a real Greek island rather than a party resort and Stathis and Maria are excellent hosts. Highly recommended.