The apartment was very cozy and clean - it is even better than what is shown in the pictures, with all the amenities listed (hot water, food for breakfast, wifi and even towels).
The location is perfect: at the heart of Madrid, with 5min walk from Museo del Prado, 10min from Parque do Retiro and only 2 blocks away from the closest metro station.
On the top of that, Paula was an amazing host. Right before arriving, she gave me excellent tips on where to go, eat and do in Madrid. She was also very understanding, letting us leave our luggage a bit after check-out time. All in all, lovely hosts and extremely helpful.
We had a very positive experience and would definitely book it again on our next visit - I just hope it will be available.