Overall we had a great stay at Nats place. As with any place there are pros and cons.
Pros:
Nat is Great - She met us at check in and went over everything we needed to know including suggestions for food/entertainment in the area. She suggested Santo Spirito area for us as young people and we ended up going almost every night for supper! She had lots of maps/brochures etc that had all of the info you might need for your stay. She also called a cab to the airport for us on our last day
Location is Amazing - You could not choose a better location for exploring Florence on foot. Less than 15 minutes from the train station and less than 5 minutes to almost anything else you would want to see. Cab to the airport cost 22 euros.
Apartment is huge and clean - way more than enough space for 2 people and had most of the comforts of home (no facecloths so if that is important to you bring your own).
Cons:
The tradeoff with the amazing location is noise. The bed is next to 2 huge windows and it is Very noisy almost all night long. At times it can sound like a mix of a party and a construction site. We bought ear plugs but still found it almost impossible to get a full nights sleep. For a short term stay the tradeoff for the location may be worth it. We were there 5 nights and if we were staying much longer it would have become a pretty big hassle
The water temperature for showering was very sporadic and unpredictable. If you managed to get hot water it was often scalding hot and you had to take advantage very quickly because it would only last a few minutes.
The stairwell - We did not mind climbing the 6 or so flights of stairs but the stairwell currently seems like it is halfway through an abandoned renovation project with exposed pipes, tools laying around and half working lights. It didn't bother us much but if you are travelling solo you may find it a bit intimidating as we also rarely saw anyone else in there.
Overall this apartment is a great spot to explore Florence and you could not ask for a better location and host but every spot has its plusses and minus' so you just need to decide what is most important to you.