We were two couples staying in Tuscany for a week in June 2014 at this property. We had opted for the larger of the two areas of the villa because we wanted exclusive access to the pool. The villa had enough space to sleep about four families - it was huge! The pool is not heated, so if you are big swimmers, don't go to Tuscany in Spring - the weather was wonderful, but the pool was too cold to use. I imagine it would be glorious in the heat of the summer though. Our favourite spots were in the roof top hot tub at night, and the little bistro table look-out spot beside the pool in the morning. On a clear day, you can see all the way to Siena. The bathrooms were all modern and updated - a delightful treat to have in a 300 year old property. The beds were ok - typical Italian beds - a bit too short for us tall folks, and no "king size" beds. For us, that wasn't the reason we were there, but it could be a deal breaker for some.
You would need a vehicle to get there, or take a cab from the Siena train station. It's pretty easy to find using the directions the property provides to you. We saw there was one bus route close by that ran once daily to Siena in the morning, and back again in the evening, so if you were relying on trains and busses, it is possible to stay there and still tour around. There are vineyards with wine tastings within a short drive or longer walk (but still do-able for the avid walker). The property is known in the region for it's olive oil, and I recommend bringing some back - it really is the best tasting olive oil I've ever had.
I really want to take my extended family and live there for the summer one day. It's amazingly beautiful, and the property management is very accommodating and helpful.