We were very pleased with the apartment - it was located within easy walking distance of the centre, and very close indeed to the Parco Sempione and the Cimitero Monumentale.
Although we arrived very late (after midnight), Marco's friend Enza waited patiently for us to give us the key and show us the place, and throughout our stay, Enza responded extremely quickly to every message we had. At one point, a fuse blew and we lost electricity from the sockets in one room - Enza had that sorted out within a day.
It is a pretty old apartment, with some old-apartment issues (like a couple of the windows were hard to open/close), but it is well kitted-out and is kept very clean.
I would overall recommend this without hesitation to anyone looking to spend some time in Milan in a great location at a reasonable price.
Thanks Marco and Enza!