The location, convenience, and the appointments of this apartment cannot be beat. Donatella let us drop off our luggage early as the place was being cleaned so that we could go out and enjoy the city while being unburdened with our stuff.
And, goodness, let me say another word about the location! You are within easy walking distance of really everywhere you want to be in Florence. The museums, restaurants, Duomo, etc. are all within easy reach. It's really in the perfect spot.
Other guests have mentioned the noise from the piazza--while this is indeed audible at night, if you bring a set of earplugs your won't be bothered.
A small note about the WiFi: the apartment has it, but the carrier (Vodafone Italy) was not reliable about maintaining a strong connection--they dropped internet connectivity intermittently. The WiFi is good for casual use, but don't count on it if you need to keep a long-term connection to a work VPN.