The flat was very clean, very modern, and even had a nice smell. The room was small but had more than enough storage space for 2 people, and it was a perfect base for exploring the city due to its nearby metro connection.
The air conditioner is an incredible amenity and makes the room very comfortable, even in the heatwave we encountered.
Marcel is a good host. The fact that the living room and kitchen are for host use only means that we did not see much of Marcel and felt like we had a lot of privacy. However, this meant we had to buy ready-to-eat food every day.
Marcel's English is not fluent but still very good, so communication should not be a problem if you do not speak Spanish. The rules are clearly written in English in the room and explained in Spanish in person.