We stayed for a weekend. The location of the apartment was great, the centre (cathedral) can easily be reached by foot and access to the Metro is right around the corner.
CheckIn is easy, we picked up the keys near the central train station and Simone was very friendly.
The apartment isn't huge but has a nice size and a comfortable bed. It doesn't get very hot even in summer and is really comfortable with the AC when it does get too warm.
The place itself is quiet but you can hear the tram right outside the street (at night too). As a light sleeper you might want to keep that in mind (although that will come with any apartment near the center). For us it was no problem.
Right across the street there's a korean restaurant (KimPap) that is REALLY good, also the people are amazingly friendly.
We can absolutely recommend this apartment for anybody who wants to be in Milan, especially because of it's great location.