Vanessa's place is in the perfect location to explore Madrid - it's in a really cute/trendy neighborhood (Chueca/Malasana), and is walking distance from the Gran Via, and to several museums. There is a great grocery store nearby, lots of restaurants and shops, and is about a 5 minute walk from the Metro.
The place is smaller than it appears in the photos, but the bed is very, very, very comfortable. There is great hot water/water pressure in the shower, and the wifi was consistent and fast enough to stream videos.
Additionally, Vanessa is a great hostess. I had a lot of problems arriving (a delayed flight, a missed connection, etc), and she was easy to reach throughout the process, and very accommodating of my constantly changing plans.
The apartment is in an older building, so there isn't a lot of protection from noise in the corridors, but the neighbors in the building did not make noise late at night. It also has a slight smell which is common for old buildings in Europe, but might be different for American travelers who aren't from big cities.
Overall, I would definitely recommend this place!