Cristian is an extremely helpful and attentive host who speaks both English and Spanish. He was very flexible with check-in and check-out times and recommended some great restaurants and bars to me and my friends.
As for his apartment, it is very centrally located in the historic center of the city and is within walking distance of several extremely popular destinations. If this is the part of the city you want to see, there is no better place to stay. Five of my friends and I stayed at the apartment, and we were initially worried about how much sleeping space we would have, but in addition to two beds and a couch, there is a cot and an air mattress in the apartment.
The only issues with the apartment were that both showers only had cold water and there was a loud bar underneath the apartment. I personally enjoyed the cold wake-up, but some of my friends would have preferred taking warm showers. The bar was active over the weekend and stayed pretty loud until 1 AM or so. Still, I would recommend this very nice apartment and would not hesitate to stay here again.