We loved our stay at Alberto's apartment. He and his colleague were very responsive and check-in was a breeze.
The apartment is literally down the street from the Duomo, incredibly comfortable, and well decorated. It's kind of a studio-style apartment, but with tall ceilings and plenty of space we never felt cramped. There's a full kitchen for those that want to cook, and a small nook/sitting area separated from the bed. It's a beautiful space and in an incredibly convenient location.
Sure--the Duomo is a block away, but my favorite part of staying here is that La Strega Nocciola is right across the street. Probably the best pistachio gelato I've ever had.