We stayed in Oihane's place for 10 days in December/January and loved it. We would absolutely stay in the apartment again on a future trip to Madrid!
The apartment: Very spacious and clean. It is a one bedroom with lots of room and has large windows that open up to small terraces. The kitchen is well equipped with pots and pans, etc, and Oihane left us orange juice, coffee, and tea.
The neighborhood: La Latina is in the center of everything. It is a 15 minute walk to the Royal Palace on the west side of the city and a 15 minute walk to the Prado on the east side of the city. There are tons of great restaurants and bars (Oihane left us a wonderful list of recommendations that served us well). Since its in the center of everything, it can be a little noisy at night -- if you are a light speaker, I would recommend ear plugs. However, La Latina is so charming and lively that its worth it.
Host: Oihane is truly wonderful. Since we had a longer stay, she offered to have someone bring clean towels and clean. Check in was a breeze. Oihane also communicated with us frequently ahead of time, even providing us recommendations for New Years and restaurants nearby.
We highly, HIGHLY recommend her apartment!