Location - Manu's apartment is centrally located. The metro stop is nearby, but we chose to walk everywhere. We did take taxis a few times and we were able to catch them very easily by walking one block to a main street.
Space - The apartment itself is very nice. The bedrooms are located at separate ends of the apartment which gave us privacy. The master bedroom was a little small, but it did have its own bathroom giving us even more privacy. All the windows have complete black-out shutters (some are automatic). This is important for me because I need complete darkness when I sleep. The apartment and the floor itself is quiet. I never heard any music, conversations, etc. from the neighbors. And we were respectful and quiet too.
Communication - Manu was easily accessible via the airbnb portal. I would write to him on the airbnb website and he would reply almost instantly. We did have a minor issue with the washing machine. I contacted him via the website - I was not expecting him to reply because it was so late, but he did. He also came out the next day to resolve the issue and explain to me how to properly use the washing machine.
Flexibility - I found Manu to be extremely flexible, as well. We had a friend who arrived earlier than we had anticipated. Manu allowed him to check-in before the check-in time. My friend also wanted to stay one extra night and Manu was kind able to fit him in for the extra night at.
Rental Car - I would not recommend renting a car if you're staying in this area - you won't need it. In fact, we arrived by rental car from the south of Spain. We were planning on keeping the car one extra night in Madrid, but realized quickly that we didn't need it in this area and it might be more of a headache to deal with a rental.