Javier is a great host, on time and helpful. The apartment is just like the pictures, very artsy. Location is very centric in terms of the Madrid city. Close to all attractions. But do note the apartment is in a rather old and not so "wealthy" neighborhood. The building is currently under construction, so it smells a little. If you are sensitive to such smells, you might need to reconsider. The air conditioner works really well.
I guess the biggest attraction of the apartment is the artistic style. So to keep that feeling there was a small trade off in functionality, which I think is fine for people that came after it. I always thought I was living in a piece of art.