My partner and I spent 10 days in Florence in the middle of summer, and could not have hoped for a better space to be in during that time. The apartment has air condition, which was a very welcome relief from the superheated streets during the daytime. What's more, there's a hammock that is perfect for reading in, as you wait for the city to cool down a little. Nights were great too - all windows in the apartment go out over a little courtyard, so there was no noise from the streets at all.
The apartment is in a pretty fantastic location also - about 5-10min away from the Duomo on foot, and 5-10min from Santa Croce, all pretty much a straight shot. There's tons of great dining very close by, and some of the best gelato in the world, too!
I'd come back in a heartbeat.