Nothing, but if you are on foot, the hill up to the place is quite steep. It is not for the unfit or very elderly, but since it is only 7 minutes walking, it would be a two minute cab ride from the port.
La Posidonia Residenza is only a 7 minute walk from the Port, yet on a high hill, so is quiet and has fantastic views of both the Argonese castle and the port. Newly renovated, it is clean, has good internet access, a kitchen (stove top, but no oven), a clothesline for drying clothes, two TVs, a safe, and anything you need for a medium to long stay. We were there for five nights in April-- we had two balconies, one overlooking the port, the other facing the castle. We were provided with chaise longues so could sunbathe on the terrace. The place comes with toilet paper, but no soap or other items (you can buy some at the reception), but the grocery store is only about five minutes on foot. We took local transport everywhere, which, while slow sometimes, worked well and was better than trying to find parking. The guys at reception were very nice and helpful. If you want a simple, clean place with fantastic views at a great price, this place is for you.