We've stayed a couple of nights in January in Marina's place, and it was a very pleasant experience. This place is all about location, I doubt you would find many apartments with such a magnificent view, your own terrace, and just a few minutes from the Ponte Vecchio.
Host was extra friendly, good communication, and was kind enough to let us check-in a bit early. The place itself is a small two-floor apartment, located in the historical (hence, pretty old) building. So don't expect any high-tech, save for TV. :) It does have a full kitchen, as well as washing machine and bath tub.
The only real downside of this place is that you have to climb a steep hill and quite a few steps to get there, so be ready for it and you would be well rewarded.
I would recommend this place to a couple, or a small family who want to enjoy great city of Florence.