We spent 3 days in Madrid, the location of the apartment is super central, you can easily walk to the main attractions. The size is perfect for 2 people and it is well equipped for a shorter stay.
The only issue we faced was the ongoing construction near to the building. Unfortunately, the isolation was not enough to cancel out the noise and the work started early in the mornings which was very disturbing. My advice is to try to ask the host in advance if any work is expected around the building. Other than this we had an amazing stay in Madrid, and can only recommend the accommodation and Francisco as a host!