We recently spent 3 nights at Mulino di Firenze, and we will definitely go back! The only drawback - and it really isn't a drawback - is that you either need to schedule your time in Florence city center around the free shuttle offered by the hotel, or take a cab (approx. 17E each way). But we knew this going in, and we were happy we chose this wonderful place. It is beautifully decorated: the room (we were in a junior Suite) was spacious, decorated, comfortable and all we could ask for; the grounds and common areas were a great combination of old-world antique with modern accents; the bar and restaurant were great.
The food at the restaurant was some of the best we ate in Italy. Breakfast on the outside deck was beautiful and peaceful. The pool area was great for a glass of wine and taking in the sun.
They do have a free shuttle that goes into town a few times in the morning, and return trips are in the afternoon. These times didn't work with our schedule so we opted for cabs. We actually walked into town one morning, but it is a bit of a hike so I wouldn't recommend it unless you are used to walking.
But for a place to get away - especially after a long day in Florence - this place was perfect for us.