Our stay in Florence was great, the flat is really centrally located. We never had to take public transport (we came & left by train). The flat is very silent, with closed windows we never heard a neighbor. Having air conditioning is very appreciated in summer (the sun is hitting hard). And overall the flat is well equipped.

The only 2 negative point were the electricity, using more than a couple device and the power is switching off, you have to unplug devices around the flat, re-switch it on & try again. And the water pressure in the shower is really low, sometimes nearly stopping (I guess when my wife was using tap water in the kitchen)

Be careful, there is no wifi and the free wifi around in the city is not working very well. So investing in a sim card with data could be helpful (your stay in Florence will be much nicer if you book tickets on internet instead of queuing a lot)

PS : climbing the stairs is good sport, be ready for it ;)