I stayed for over a month at Grettel’s place. The apartment itself is beautiful and centrally located (~2 mins from the BART and muni stations). There is 24/7 security in the building and tenants have access to the rooftop and gym. Though there are some interesting characters who frequent the surrounding area, the area is safe. No one ever gave me any trouble at all, but, like with all of SF, you should be aware of your surroundings. I would definitely stay there again.