We stayed at Pietros last week and it was perfect. It’s really just a short walk to the colosseum as described.
The communication with everybody involved in renting the apartment went smoothly and there wasn’t a single problem.
The apartment itself was very clean and we didn’t have one problem. Everything was just working as it should - the air conditioning, the oven, microwave,... - there wasn’t a problem with anything.
If you’re looking for a place to stay in Rome we can only recommend Pietros place.
Best wishes from Austria