We enjoyed our stay at Studio S. Maria Novella for 5 nights. The location was close to the train station for a quick walk with luggage and also an easy walk to all the sights in Firenze. The studio was bright and very clean and the kitchen is ridiculously stocked with tons of equipment if you plan to cook in the apartment. We chose to sleep downstairs to avoid the stairs which are tricky but the upstairs bed would have been more comfortable.
Please note that this is a very small space and is more suitable for a couple of nights rather than 5+.