We stayed 3 nights in Elena's apartment and it was perfect. Super clean, good beds (including the sofa bed), great bathroom+shower, plenty of space for the 4 of us.
It's on the 1st floor so only a few steps up but there's also a lift for when you have luggage with you. Check in/out was exactly has planned and completely hassle-free.
The apartment is quiet as it's away from the (not very busy) street and the balcony opens onto a courtyard.
You're 10 minutes walk from the Duomo and the historic centre and there are plenty of restaurants just 5-10 mins away. There are small shops to buy essentials nearby and a supermarket within walking distance.
The flat is just inside of the restricted traffic zone and there's an underground car park (outside the zone) just 10 mins walk away for EUR 20/day.
I would definitely stay there again and can recommend it!