We stayed almost 2 weeks in Serena's apartment. My husband, son (12 yo) and me.
The location is wonderful, beutiful, but it is uphill, a mile away from Proto Rotondo, and 2 miles away from good beaches. There is a bus running every hour (during summer) between Porto Rotondo and Olbia. It is almost always late 10-30 minutes, so waiting for it on the sun is an ordinary thing if you do not have car. From Porto Rotondo there is are free shuttle buses to the beaches every 30 minutes. These buses are sharp on time, but always crowded. So at last we ended up walking to the beach and back home. (4-5 miles a day, half the walk next to the main road without pavement) The supermarket is 1 - 2 miles away in any direction. Imaginge waling 2 km with heavy stuff next to a busy road which has no pavement.
So all in all, you need a car to stay comfortably in Serena's apartment.
Serena otherwise is very friendy and helpful. Unfortunately we do not speak Italiand, so we had to use (SENSITIVE CONTENTS HIDDEN) translate to make ourselves understood.
We bought a sim card (30 EUR / 30 GB / 1 month) to get Internet, there is no Internet in the house.
In the apartment the furniture is basic, old, and not really in good shape. I think it is meant to be rustic, but not all furniture is functional. Please mind that the sofa is suitable for sleeping only in case of emergency. It is old, smally and not comfy.
The beds in the two bedrooms were comfortable, but some of the cupboards had no shelves, so it was difficult for us to use them.
Kitchen is not well equipped, there are basic stuffs for cooking only. Boiling pasta or making scrambled eggs is OK. But I did not feel I woud like to try to make more sophisticated food there. Btw, bring your knife, as knives are really bad in the apartment.
Only the living room is air conditioned, in the bedrooms they have fans. but temperature goes somewhat down during the night, so opening the window is a remedy against heat at night, however there are plenty of mosquitos and no net agaisnt them.