The flat is amazingly designed, it has all the comforts you might look for a nice stay, it's well connected via buses to areas such as downtown and golden gate as well as being in the front of the university.
The area is quite and feels safe, during the stay we didn't see any possible treat around the area (which you can definitely find elsewhere, e.g. around Tenderloin).
I gave 4 stars instead of 5 just because we had noise coming from the floor above 2 nights out of 4 (probably a shower at 2am and a washing machine between 1 and 2am) and because the host even if kind and accomodating wasn't so responsive.
However I will definitely recommend this place to anyone looking to visit SF.