I stayed in Marco's apartment for 9 nights. I rented the apartment because of the high reviews and I was traveling on a budget.
The Good:
Marco is very nice and I believe he is honestly trying to provide nice, comfortable accomodations. He helped me with my bags upon arrival and departure and helped me call a taxi.
The location is wonderful. I prefer to be outside of the tourist center.
The apartment was clean and as pictured. The small kitchen is well equipped including a new microwave and kettle.
There was a good selection of Italian channels on the television.
Not So Good:
The stairs are very steep and uneven. Not good if you have mobility problems or are accident prone.
The apartment is missing basic things like an iron and ironing board. Better towels - I was given towels that looked like old, discarded towels no longer wanted at home. No trash can and toilet paper holder in the bathroom . Needed more hangers in the wardrobe.
The bed is super firm - not comfortable for me. Only 2 pillows were provided - I have 4 on my bed at home. There's a bar right below the bedroom that can get loud sometimes. If you are a light sleeper, you'll need earplugs or plan to sleep on the sofa bed.

Overall, the apartment is good for budget travel or short stays.