Marco's apartment is beautiful and relatively walkable from various points of interest around Milan. My main issue with my stay, however, was the check-in procedure. I spent three weeks in various parts of Europe for a class through my graduate program, with Milan being the last stop on my trip. Because of school scheduling and the nature of traveling in a foreign country, I had to check in later than I'd initially communicated with Marco, which was a problem for him as his procedure requires that he be there to hand off keys--at every other AirBnB I've stayed in, the keys were simply placed in a lock box outside of the building which allows for much greater flexibility to both guest and host. Marco scolded me for arriving late once I got there, in addition to sending me angry messages, and then continued to scold me for bringing suitcases that he deemed "too heavy" (he carried my suitcase up the stairs to his apartment even though I indicated that I was perfectly capable and happy to carry my luggage myself; it would have been a nice gesture had he not berated me the entire time for the size of my bags). Also, there was not air conditioning in the apartment, which was not indicated on the listing at the time that I booked my stay--this meant that I had to leave the windows open which resulted in over 30 mosquito bites.
Aside from these issues the apartment itself was beautiful and interesting and the location was fine--rating would be lower if not for these things.