Overall my stay at Juana's place was very pleasant. The location is great: most interesting sites are within 20 minutes walk and the Tribunal metro is close by for longer trips or if you need to get to the airport. The apartment is spacious, the bed sheets were new and clean. Overall, the level of comfort was great. I also enjoyed exchanging with Juana and she was very excited to give advice about places to eat, bookshops or sites to visit in Madrid. Be careful however, she speaks Spanish and French, but if you only speak English, the exchange might be less frictionless.
When I arrived, I had a little problem getting into the apartment block, when I've discovered that the flat number was incomplete. Although the host seems to have been waiting for me in the flat, I was unable to enter and their phones would not answer. Luckily, after one hour my messages have finally gone through and I was able to check in. The event didn't spoil my overall experience, but make sure you check the exact flat number with Juana before arriving.
All in all, I will definitely recommend Juana's place to anyone visiting Madrid for tourism or business trips.