My son and I (17 years old) had a wonderful stay in Chiara’s apartment. I am not sure you can top the location. Imagine cutting down a small alley and popping out in Piazza Navona. It is just a short walk to the Pantheon, Trevi Fountain and the Spanish Steps. It is a very manageable walk to both the Colosseum and Vatican (~20min) - that might sound long to some, but you walk by so many great sights en route that it seems like nothing.
The air conditioning was great. Fans in the bedrooms were helpful for us Canadians used to cooler temperatures. We had no issues with comfort due to the heat.
The apartment was perfectly clean. There was perfect communication. I would happily return and recommend her place to family & friends.