Carlotta's place is literally 5 minutes walk from Duomo and about 1 minute walk to the main street, shops and restaurants. If you are looking for location this place is for you. Carlotta is very quick at responding, you can rest assured that she will take care of you the entire stay. She lives in the apartment next door I believe, but we felt like the whole place was private and for ourselves. Only when we needed her help could we sense her presence. For example, it was raining a lot when we were in Milan, I asked Carlotta if she had spare umbrellas and she put 2 big umbrellas by our door. It definitely saved us money and trouble. The place is also clean and stylish, not the biggest 1 bedroom you will find, but for the price, location and style you cannot find any hotel (or I doubt another apartment) this good. The apartment is gated so you will feel safe inside.
Only warnings: 1) I don't think there is a microwave in this apartment, so if you desperately need a microwave then you have to evaluate everything else I said against that need.
2) The elevator system is not what we are used to in the U.S., Carlotta will teach you how to use it. If you don't operate it properly it will affect other residents' usage (there was another resident who didn't operate the elevator properly so we had to walk downstairs and actually close the door properly on that floor so the elevator usage can be restored). So if you can't be considerate then second think before booking.
Otherwise this place is HIGHLY recommended.