The place was very nice, clean, and perfect to accomodate 6 people (it could even accomodate more due to the pull out couch). The design was modern for the rooms and bathrooms. We did not use the kitchen but it doesn't have a window so I would recommend to be careful in what you choose to cook. The place felt a little but humid overall, especially after the showers, but we did not really stay much in the apartment (just overnight) so that wasn't a huge issue for us. The street the apartment is on is very calm and well located - we walked everywhere in Madrid, even when it was raining. We could hear the neighbors talking one night but otherwise it wasn't very noisy.
The host was very responsive before and druing our stay while was highly appreciated. The directions regarding the apartment and its access were also very clear.