Everything was great. Location was perfect! We were a bit scared because of a not very nice comment we read from the week before we were travelling. It's true that the shower has a curtain because it's missing a glass door but it wasn't a problem at all for us. We didn't have any issue with the bed, it was actually better than in the photos (we saw two singles bed with a double mattress in the pics, but it was actually a full double bed, I guess it was recently changed).
It's true that there is a small humidity stain at the bathroom ceiling, but I don't think that would be a problem for almost anybody.
Also, there's a very nice café next to the apartment called Mo Si Caffeteria where we had very nice and cheap breakfast everyday.
If we ever come back to Firenze we will try to stay at this apartment for sure again!
Grazie mille Niccolo!!