I was very happy with our stay.
The apartment is up a few flights of stairs, but the elevator works fine. (Be sure to remember which apartment it is before you leave, though -- if you take the stairs, it is easy to get confused.)
The apartment was quite spacious and comfortable. It fit five (two couples plus one single) easily and could have fit three couples easily. The kitchen / dining room was big enough for everybody to eat together. It was a little crowded if more than one person wanted to cook at a time -- you needed to choreograph your cooking slightly.
We turned on the TV once, I think, and just didn't bother the rest of the time.
There were simple staples provided: salt, pepper, oil, sugar, tea, coffee, soap, toilet paper, dishwasher detergent, laundry soap, etc. The kitchen equipment (cutlery, knives, pots, pans, etc) was perfectly adequate. You had to hold the stove's burners down for a while to make sure they stayed lit, but we were trained on that ahead of time. The refrigerator, dishwasher, and washing machine worked just fine; we never tried the oven.
There is a small back porch which has a laundry line. There were also clothespins. The laundry line worked well for us when it wasn't raining, and the large laundry rack worked well for us when it was raining. (The apartment is so large that we had space to set up the rack inside without a problem.)
It was warm enough in the apartment, which is good because there were not any extra blankets. (The entire building had a water shut-off for part of the day on our first day due to some problem with the heating system, but it was fixed by the time we got home, and we were kept well-informed.) I do not remember any extra pillow, either.
The beds were comfortable. There was LOTS of closet space in the bedroom I used. The other "back" bedroom had drawers but no closet, but there was a wardrobe in the hall. The "front" bedroom had drawers but no closet, with a closet in the hall nearby but we really wanted to use that hall wardrobe as a coat closet.
The "front" bedroom had a glass door, not a wooden door, and was quite near the door to the apartment (and closer to the street), so don't put your lightest sleepers in that room. The "front" bedroom is the only bedroom with an ensuite bathroom, the "back" bedrooms have bedrooms across the hall. We really appreciated having three bathrooms to go with the three bedrooms.
The biggest bathroom's shower had weak hot water flow; the other bathrooms had fine flow.
The apartment had AMAZING shutters which blocked the light extremely well. I started leaving them open a crack so that I could have some awareness of what time of day it was. Otherwise, I would wake up and think it was the middle of the night when really it was 10AM. The shutters also helped to block out the street noise.
The apartment is on a very busy street, so in the rooms which faced the street (the living room and kitchen), it could get be very noisy. The shutters helped quite a bit, but did not block it out completely. The balcony also faces the street. It was too cold or rainy to really want to sit outside while we were there, so I'm not sure, but I think the noise would have kept me from sitting outside much.
The two back bedrooms were quite a long way from the street, and very, very quiet with the windows closed and the shutters down.
The apartment is a little ways out from the centre. I generally planned on a 20 or 30 minute walk to get anywhere. (There were convenient buses nearby, but I usually wanted the exercise.) It is very pleasant to walk along the Arno to get to town, especially if it is not raining.
There is a very very basic grocery store very close by and a reasonable one about four? six? blocks away. There is a coffee shop about a block away and several other cafes and bakeries within about three blocks.
There is a park right across the street.