My husband and I stayed at Cosimo's place for ten days on our recent trip to Florence and were quite happy. The location was great - just across the Ponte Vecchio from the main sights in Florence, tucked a little out of the way but still easy to get to everything. There is a wonderful market right down the street at the Basilica de Santo Spirito, and a great grocery store just on the other side of the river within a five minute walk. Best of all, every morning when you walk out, you start your day in front of the Palazzo di Pitti.
The apartment had everything we needed, even for a lengthier stay. Our cooking was mostly breakfast and a few light lunches, but we had everything we needed to cook our eggs and our pasta. The shower was roomy enough even for my 6'2" husband. There was a washer so we could refresh some of our clothing during our stay, and a rack so we could air-dry them. The bed was fairly comfortable as well, and we appreciated the extra linens and pillows that were provided.
Best of all, Cosimo was very responsive. He was right on site for our check-in, even though we arrived at 10AM, and responded quickly to any small request or query we had. Would definitely recommend this as a great place to stay in Florence.