Sonia's place was just as shown in the pictures. She is a wonderful host, always very attentive to our needs. We didn't get to meet her in person, unfortunately, but she checked in with us throughout our stay and even helped arrange for transportation.
The apartment is very nice and close to many of the major sights. There are plenty of restaurants, supermarkets and ATMs nearby. Check in and check out were super easy too.
Overall, we had a wonderful stay in the apartment and a great time in Madrid. We hope to return one day and will make sure to stay at Sonia's apartament again.