We stayed in 4 campsites and around 11 hotels on our European trip. This was the worst accommodation on a campsite (but it isn't bad), but in fairness they do warn you of the short coming, but could be good for you, just be certain before booking.
This is interesting accommodation, essentially a mobile home (so metal, i think) divided down the middle. In your half you get a bedroom (with fridge) and a bathroom. The other half is a mirror of your accommodation.
Outside you get small space with a table and two chairs.
The accommodation was clean and well prepared and in many ways is like a hotel room.
As you can imagine mobile homes are a little flimsy. Our first night was fine, as we were the only people in the caravan, however on the second day we got neighbours. You could hear every word they said, as it was Spanish, we couldn't understand it, they weren't particularly quiet. Even if they were you can hear them using the washroom! and they didn't realise they had door handles that help shut the doors. Plus when they moved around the caravan juddered.
On the plus side the campsite had a good restaurant and is very handy for the lovely City of Siena.
For us, we would not stay again, I could not imagine spending more than 1/2 days in this type of accommodation (shared mobile home). I think the site has other types of accommodation and would give them a spin if we went back as the site is very pleasant.