Great location, friendly host, interesting surroundings. Easy walking distance to Villa d'Este and Villa Gregoriana. Parking is in the nearby public car park, which is expensive, but that's going to be the same for any nearby accommodation. This part of Tivoli closes up by about 8.30pm, so make sure you eat before then! There's a 24hr supermarket within walking distance if you get desperate.
Our bed was very comfortable, and the room was clean. There's a common area with tables and chairs for all guests to use.
Unfortunately, the shower in our room was hopeless. Hot water lasted around 5 minutes, and the shower itself was as much use as a water pistol. Literally a dribble of (cold) water. Breakfast is around the corner in the same building in an ex burger joint. Coffee was good, otherwise very basic, and they seemed surprised that we might like milk for coffee and cereal. They had to go and look for some. How do Italians eat cereal if not with milk?
We were booked for two nights, but left after one and returned to Rome. We are easily pleased - a clean bed, a good shower, and decent coffee is all we ask, and in 25 years it's the first time we've ever done that. I don't think we should have to inform the host that the shower isn't working - they should check these things between bookings themselves.