We had a great time in Laura's apartment! It's very central and Laura was very sweet and helpful and told us about a special event in Siena that was absolutely amazing.
There are a couple of things I'd recommend knowing before you stay: First, there are a lot of stairs. We had read that there were a lot of stairs but there were even more than we expected. The stairs meant that we would often stay out a little longer/not go back to the apartment during the day, despite the location being extremely central. That said, we also didn't gain weight while eating pasta and pizza all week, so that was great and probably partially because of the stairs!
If you plan to wear heels at any point during your stay in Florence, I strongly recommend a pair of tiny slip on flats (the kind that roll up into a pouch) just for going up and down the stairs. I didn't have those and couldn't manage the stairs in high heels and it did put a little damper on going out sometimes.
Second is that I'm 5'11" and my husband is 6' and I wouldn't recommend being much taller than that and staying in the apartment. The upstairs (where the bed is) has an angled ceiling and we hit our heads on the closet with some regularity. I'm sure over time you'd adjust, but not likely within a week. All told, the apartment was clean and the roof-top terrace was lovely.