Our group of 16 stayed at the villa and found the accommodation as beautiful in real life as in the pictures. The buildings and rooms were as pictured- particularly the main house was gorgeous and the gardens were stunning. We had towels changed after 2 days which was a nice touch, and they provided pool towels.
While we appreciated having a pool (very unusual for Rome), we did find it in a bad state of repair - the stairs had loose stone boulders which were dangerous and there were rusty nails sticking up in places where the wooden panels were broken. We all got splinters in our feet from the wooden panels around the pool. They also had a builder using dangerous saws in the communal areas while we were staying there - not baby safe and very noisy. I had to complain a number of times for this to be stopped.
Overall though we had a very pleasant stay and liked the closeness to Rome while still having lots of space and a pool to cool down. I would recommend that you check about the sleeping arrangements given the set up some beds in the living room if the accommodation is booked for 20 people.