Gaia's apartment was perfect for my stay in Florence with my wife. It is very convenient to get to from the Santa Maria Novella train station (not even a 5 minute walk) and it is located on a great public plaza that has plenty of energy and food / drink options.
The apartment was exactly as advertised. It is newly renovated with very nice finishes and an absolutely MASSIVE shower. After experiencing a very small shower in Venice, this was a nice change of pace.
Everything you would want to see in Florence is easily walkable (even the Piazzale Michelangelo which is further away but can be done along the River Arno and is very scenic). If you are doing a day trip to Pisa or wineries in the Chianti region of Tuscany, virtually all your tour groups will have you meet them at S.M.N. train station so again, you're right there.
The only catch is that it takes 99 steps to reach the top floor of the building to the unit, but if you've been walking around all day already like most tourists in Italy, another 100 steps won't kill you. It also feels very secluded and safe for that reason as well.
I would recommend this apartment to anyone visiting Florence.