Andrea's place is about 20-30 minute walk from Firenze Santa Maria Novella train station, and is near all the coolest and most interesting places to eat in Firenze. It's also near clubs, but you don't hear any of the noise from them. I found that walking around the city was delightful from this location. Andrea provides a list of suggested places to eat around town, as well, and I found this useful.
Do note, there are some steep and somewhat narrow stairs (at least it will feel this way for North American visitors!) Andrea's father helped my with my bag when I arrived. I just had a regular carry-on and a backpack, nothing huge!
Definitely a wonderful place and I felt like I lived there, it was quite comfortable.