We had an excellent stay and experience with this flat. I would stay here again.
First, Andrea was helpful in providing information on where to park, transportation options and personally met us when we arrived. He gave us a good orientation to the unit. It's located on the main street of Siena, close to everything. Andrea even pointed out favorite pastry shops and restaurants. High integrity guy.
The flat was very clean and spacious. He provide extra sets of towels which was a plus. The unit has a washing machine and drying rack which we used and was helpful. He provided us some basic food to get started - yogarts, fruit juice.
There's a great view from the dining room. The unit keeps a fairly even temp and just opening the windows gets a nice cross breeze. No screens on the windows but had no issues with bugs. As with any unit in the heart of the city, it's noisy if the windows are open. Closing them blocks most of the noise. The neighbors are quiet.
The unit is on the 3rd floor. There's an elevator or about 100 stairs to climb.