Santo Spirito Palace is in a fantastic part of Florence, away from super tourist-y areas. Piazza Santo Spirito is great with a number of restaurants right in the piazza. We had a fantastic dinner at Osteria Santo Spirito and also had quick bites for breakfasts and lunches from various other spots in the piazza and all were great.
Federico's place is amazing. It's well kept, his associates that handle check in or other questions are quickly responsive and helpful, and we found everything to be as expected and often better. Our family is 6 people, including 4 kids ranging from ages 7 to 18, and we had plenty of room and never felt cramped.
I will add one piece of information that some other reviews have mentioned also. If you are traveling with kids and/or looking for quiet nights you should be aware that Piazza Santo Spirito is a lively place when it gets late, even on weeknights. Maybe because we happened to be there during a particularly warm stretch of weather in March it was louder than usual, but know that the noise from the piazza does go on well into the early morning hours. Two of the three bedrooms have windows on the piazza and those are obviously the most affected.
This didn't severely impact our stay, but it's important to know what to expect.
Overall, great experience at Federico's place.