I had a perfect stay with Carmen at her home. I stayed for over a month (study abroad), and Carmen made sure I felt right at home. The apartment is in a very safe neighborhood away from the louder, more touristy areas of Madrid; but close enough that you can hop on a bus and be downtown quickly whenever you want (bus stop less than a minute walk from apartment). There is a very nice trail down the street that is great for walking, running, biking, etc. And, there is a grocery store basically around the corner.
The wifi worked perfectly. Everything about the apartment exceeded my expectations. Carmen even made me delicious meals and helped me practice my (very limited) Spanish-speaking skills! Can't say enough kind things. 11/10.