We had a great time in Florence and staying at Serragli Loft! The place is extremely spacious and the location is great. It's just north of the trendy Santo Spirito neighborhood, and we were easily able to walk to everything in central Florence.
Some things other folks have mentioned: it's on the third floor with no elevator, so just be prepared to carry your things up. The loft itself is furnished with the essentials, although we had to get a few cleaning supplies ourselves. We, too, noticed a fair number of mosquitoes buzzing about even though we kept all the windows closed and the AC on (not sure what's up with that...) The owner is responsive to messages, but gave basic responses and didn't clarify all our questions.