All in all, I can recommend Francesco‘s Airbnb. He is very nice and always available for questions. The room is small but fits if you want to walk around Rome. By foot you are approx. 10 mins away from the Colloseum. You can reach the Airbnb easily by taking the bus from Termini.
The room has everything you need for a stay in Rome. Also there is a beautiful terrace where you can sit in the evenings!