There are many great things about this place. The location really is so central with lots of great cafes and restaurants nearby. The flat itself is calm and there is no street noise at all which is great. We came as remote working nomads and it worked out fine. He has an office space at the other end of the flat and in our bedroom a desk too (even if very small). The internet connection was very good.
Juan Jose was very responsive if anything broke - replacing it immediately. He was a great host.
Some less good things were the two single beds in our room - not great for a couple, and there isn't much space for storing food - especially if you like to cook and stay for 1 month.
The thing that was hard sometimes were the other 2 guests! We had to clean up after them constantly and they used up all the shared resources (toilet paper/water/coffee etc.) within days. But that wasn't Juan Jose's fault!