This apartment is super central, HUGE, and very comfortable. Matteo is also a lovely host, and so easy to contact/interact with. We were just a couple staying, but 4 people would not feel cramped here at all, which is a rarity for such a central AirBnb. It is literally steps to the Duomo.
One thing to note though, is that although the apartment has windows in all the rooms, they are all interior-facing windows (e.g. into a small interior courtyard). Because of this, you can't really see out into the street/any views, and they all have curtains. I get claustrophobic and this was hard for me, though mitigated by how spacious the apartment is itself. Just an FYI for others who might have this issue.