I very much enjoyed staying at Carlotta's place. It is super conveniently located and just the right size for one or two people. Her husband met me to let me in and acquaint me with the flat. He spoke very good English.
After the first day, the doorman of the building recognized me and made me feel welcome. The neighborhood, just a couple of blocks from the Duomo has everything you need nearby. There's a small upscale food market within half a block and there's also a laundry within the same distance, though you can of course use the washer at Carlotta's place. Note: the laundry nearby can be relatively expensive, but they do a good job.
Public transit is of course also near, so it's extremely easy to get around.
The building itself is very quiet with just a few apartments / offices per floor. I rarely saw anyone coming or going while I was in and out several times each day.
I fully recommend Carlotta's place and would stay there again were I to visit Milan.