The apartment is very quiet despite being located on a busy street. Everything we needed for our stay was there including a small kitchen. The location of the apartment on the fourth floor without an elevator should not be a problem for anyone reasonably healthy. The distance from the house to many Madrid's points of interest is very short so the apartment is a good place to stay for someone looking to see Madrid's museums, etc. The wifi in the apartment is quite stable and fast so working from there shouldn't be a problem.
Overall we enjoyed our stay and would gladly stay there again if we visit Madrid one more time.