I traveled as a single woman. I felt very safe at Dulce's place. There is an outdoor door with a lock then the front door with a lock. The neighbors were also very friendly and asked if I needed anything.
The apartment is very convenient to the key things - Three Museums (Prado, etc.), Palacio Real, Plaza Mayor, Retiro Park, Puerto Sol etc. I walked to most things but the metro is very close (2 blocks). The stop is Sol and if you wanted to you can get to main attractions on that line w/o having to transfer lines. Very convenient.
There are lots of restaurants and shops right in front of her place. There was lots of energy outside but inside the apt. it was very quiet. There was also a little courtyard to enjoy.
The apartment looks just like it does in the picture. Everything was immaculate and decorated with a woman's touch --Very clean, fresh linens, very welcoming feeling. All the appliances worked, the kitchen was fully stocked w/ dishes, utensils etc. if you wanted to cook. I would definitely stay here again, well worth it.