My wife and I visited Stia in mid Sept for 11 days. We used the cottage as a base for our travels; Sienna, Cortana, Rimini and Florence are all 1-2 hours away.
The house is very rustic as you will see from the photos, the land around it is large and very flexible; outside oven (we used to make fresh pizza), bbq, multiple sheltered seating areas and the pool.
When up in the cottage, you feel very remote, but the village is just 1.5km down the hill - we did a daily shopping trip for fresh products in under 30 min.
The host, Fabio, doesn't speak English but he's very friendly. He arranged for an ex-pat, Monica, to be at the cottage as we arrived, which helped tremendously. She was an excellent guide and happy to continue giving help / tourist advice via WhatsApp during our stay.
We would/will definitely return to the cottage but would go June to August to make full use of the pool.