TL;DR nice and cozy appartment close to Roma Termini and Colloseum.
We've stayed as a family with two children (8/5yo) for two nights and it was a pleasure. The appartment is a short walk from Roma Termini so if you arrive with a train it's very convenient to get there.
The appartment is quite close to Colloseum and other attractions. Metro basically around the corner. A small park (Piazza Vittorio Emanuele II) with a playground. Grocery nearby, a few good restaurants.
The appartment is very calm and comfortable.
The host is very responsive, very good contact, everything went exactly as arranged.
Overall great value for money.