Everything was just perfect. Mary, Massimos wife, was very warm and welcoming and took time to tell me a lot about San Francisco, the neighbourhood (restaurants, stores, bus lines etc.). Also later during my stay she was there when I had some questions.
The studio itself was also very pleasing - way more than I actually needed (kitchen etc.). Should work just fine for up to 2 persons (I was on my own, though). It's a 3mins walk to 1 California bus station, which brings you downtown. The neighbourhood felt very safe, and you had lots of restaurants and stores to choose from. It's a short walk to Baker Beach, where you can see the Golden Gate Bridge from.
Definitely recommended!
Thanks again Mary.