The apartment definitely has some big plusses. The location, quite close to the center and touristic attractions, is great! There is a supermarket around the corner and many nice restaurants. The elevator in the building and sunny terrace are also a big plus. The apartment is well-equiped and overall, we had a good stay at this apartment.
Throughout our stay we experienced a bad sulfurous smell in the apartment, coming from two of the bathrooms. Although we decided to not let this affect our stay in Madrid too much, it made our stay in the apartment less convenient.
One morning the boiler broke and we did not have access to hot water anymore. The landlord was very quick to fix this, without causing us any further trouble. Communication overall with the landlord was very good!
Lastly, the mattress in the first bedroom is quite uncomfortable and the bed definitely too small for two adults to sleep in. We overcame this problem by sleeping on the couch - but that's not what you want when renting a three bed- and bathroom apartment.