I stayed at Nico's for ten days, left for five, and came back for ten more. I fell in absolute love with the neighborhood. Once you get all the touristy stuff out of the way and eat at all the places everyone told you to eat at, settling into Santo Spirito is wonderful; it truly got more magical every day. I feel fortunate to have gotten to experience Florence from this perspective.
The apartment was also great- clean, warm (writing this in late fall), and has everything you need for a short or longer stay. Nico is quick to respond and handle anything that comes up!