I stayed at Marta's apartment for 5 nights in November and I could not be happier for choosing this place. It was an absolutely beautiful spacious and well decorated apartment located about 10-15 minutes walk to the Real Madrid palace, madrid cathedral and temple debod and other famous monuments and tourist sight seeing places.
The apartment had EVERYTHING that you need and more for the stay in Madrid and Marta was such a nice thoughtful host that has thought about every detail and has provided it in the house. She met me at the apartment and gave me so much information about where to go and marked a map with all the places to see. She was always responsive from the day I booked the place till I got there and also during my stay; and was quick to send the building manager to fix the heating system when I didn't know how to use it:) the building manager was also very friendly and gave me advice on where to go for best flamenco show and other things to do in Madrid.
The neighbourhood was safe and is in a very historical part of madrid and is so lovely with lots of shops and restaurants in walking distance.
I would love to go back to madrid whenever I can and will definitely stay in Marta's place again and again and highly recommend it to everyone. Believe me you won't regret it:)